Introducing Cisco IOS

Cisco Router IOS
The Cisco IOS is a proprietary kernel that provides routing, switching, internetworking, and telecommunications features. The first IOS was written by William Yeager in 1986,

Cisco router IOS software is responsible for:
1- Carrying network protocols and functions
2- Connecting high-speed traffic between devices
3- Adding security to control access and stop unauthorized network use
4- Supplying network reliability for connecting to network resources

Connecting to a Cisco Router
You can access the Cisco IOS through the console port of a router, from a modem into the auxiliary (or Aux) port, or even through Telnet. You can connect to a Cisco router to configure it, verify its configuration, and check statistics. Most often, the first method you would connect to router is the console port. The console port is usually an RJ-45 (8-pin ) connection located at the back of the router.

Booting Process of Router
1-When you first start a Cisco router, it will run a power-on self-test (POST).
2-If it passes, it will then look for and load the Cisco IOS from flash memory.
3-If an IOS file is present then it would expands it into RAM.
4-After that, the IOS loads and looks for a valid configuration the startup-config that’s stored in (NVRAM).

Router Configuration Modes
One key to navigating the CLI is to always be aware of which router configuration mode you are currently in (see Table 1.1). You can tell which configuration mode you are in by watching the CLI prompt.

Router Configuration Modes
Mode             Definition                                                                             Example
-------------------------------------------------------------------------------------------------------------------------
User                 EXEC mode Limited to basic monitoring commands            Router>
-------------------------------------------------------------------------------------------------------------------------
Privileged       EXEC mode Provides access to all other router commandsRouter#
-------------------------------------------------------------------------------------------------------------------------
Global mode   Commands that affect the entire system                             Router(config)#
-------------------------------------------------------------------------------------------------------------------------
Specific mode Commands that affect interfaces, routing processes,         Router(config-subif)#
or lines only
-------------------------------------------------------------------------------------------------------------------------         
Once you understand the different modes, you will need to be able to move from one mode to another within the CLI.

Command Meaning
Changes from user EXEC to privileged EXEC mode
Router>enable

Changes to user EXEC from privileged EXEC mode
Router#disable

Changes to global configuration mode from privileged mode
Router#config term

Exits from any configuration mode to privileged
mode (Ctrl+Z is also commonly used)
Router(config)#exit

Enters interface configuration mode from global configuration mode
Router(config)#interface <int>
example: Router(config)#interface fa0/0

Enters subinterface configuration mode from global configuration mode
Router(config)# interface <subint>
example: Router(config)#interface fa0/0.1

Enters line configuration mode from global configuration mode
Router(config)#line <line>
example: Router(config)#line console 0

Enters router configuration mode from global configuration mode
Router(config)# router eigrp 1 

Setting a hostname on a router:
Router#config t
Router(config)#hostname dixit
dixit(config)#

Configure NTP Server in Linux

According to the Red Hat Exam Prep Guide, you need to be able to synchronize clients with a higher stratum server. The term stratum is used to define different levels, from 1 to 15, of time servers that are available to sync with. A stratum 1 time server is the most accurate. For load balancing and redundancy, you would probably want to configure a primary NTP server and a secondary NTP server to sync with a stratum 1 time server. Now let’s look more closely at both the server and client side of NTP.

Configure NTP server
Step 1. Verify that the package has been installed:
# rpm -qa | grep ntp

To configure the primary NTP server, let’s look at part of the config file that comes with the system:
#vim /etc/ntp.conf
...
server 0.rhel.pool.ntp.org
server 1.rhel.pool.ntp.org
server 2.rhel.pool.ntp.org
...
#server 127.127.1.0
#fudge 127.127.1.0 stratum 10
The first three lines shown here are the Internet (public) NTP servers that you sync with for the correct time. The fourth server option, which is usually based on the BIOS click if used.

Step 2. Start the NTP service:
# service ntpd start

Client configuration:
With the server configured, you can turn your attention over to one of the client systems. For this example, use the Client01 system to sync with the server1 (192.168.1.100) primary NTP server.

Define server1 as the primary time server and make sure the driftfile line is uncommented:
#vim /etc/ntp.conf
...
Server 192.168.1.100
driftfile /var/lib/ntp/drift

Step 1. Use iptables to create the required firewall rules:
# iptables -I INPUT  -p udp -m udp --dport 123 -j ACCEPT
# iptables -I INPUT  -p tcp -m tcp --dport 123 -j ACCEPT

Step 2. Save the firewall rules you just created:
# service iptables save

Step 3. Then restart the iptables service:
# service iptables restart
#service ntpd restart

Step 4. Specify the upstream server that you want to sync against:
# ntpdate 0.rhel.pool.ntp.org

Step 5. Start the service again:
# service ntpd start

Step 6. Verify that the time is accurate with the date command:
# date

The next troubleshooting command is ntpq, which enables you to query for other NTP servers. Here, the only concern is the -p option, which polls for other NTP servers:
# ntpq -p

Process Management in Linux

Every time a program or command is run, a process is created for it. These processes are all unique and identified by the process identification (PID).

Here are some of the process management commands you can use:
ps Displays information about running processes

kill Terminates a process 

pgrep Finds a process based on its PID

pidof Displays all processes related to a service or command

top Monitors system resources (similar to Task Manager in Windows)

renice Adjusts the priority of a particular process

1-To view processes with more detailed information, you can use the following command:
# ps u
Or you could also use following command for more detail.
# ps aux

2-What happens if any process running on your system becomes out of control? you can use the kill command to terminate the process, even if it isn’t responding.
Syntax: kill PID

To find the PID(s) belonging to the SSH service, use the following:
# pidof sshd
4286
To achieve the same information you can also use the pgrep command:
# pgrep sshd
4286
Where 4286 is pid of sshd service
To kill the process forcefully the SSH service, you can use the following:
# kill 4286

top This command gives you an overview of processes on the system, including memory usage, CPU utilization, and more. Look the output as shown in figure (top 1.0).
#top                            
                                                                              top 1.0

You can use the renice command to change priority on the CPU.
Syntax: renice <priority> [options]
Options:
-p PID Changes process priority for a particular PID
-u user Changes process priority for a particular user(s)

The priority values range from –20 (very high priority) to 20 (very low priority).
For example following command will change the priority as -2 for pid 3874.
# renice -2 3874

Using the free Command The free command allows you to display the amount of free and used memory on the system. To do so, type the following at a shell prompt:
#free
 
Using the System Monitor Tool
The Resources tab of the System Monitor tool allows you to view the current CPU usage on the system.
To start the System Monitor tool, either select Applications > System Tools >? System Monitor from the panel, or type gnome-system-monitor at a shell prompt. Then click the Resources tab to view the system's CPU usage and Memory usage, (look figure System Monitor 1.0 ).

System Monitor 1.0

Job scheduling Using Crontab

Ther are two utilities that you can use to schedule a job in Linux 1- AT, 2- CRONTAB.
A-at
At utility is used to schedule a one-time task at a specific time. Before configuring at make sure that service is running and set start to boot by using following commands.
#service atd start
#chkconfig atd on

If you have any problem regarding service management click here to know more.
To schedule a one-time job for a specific time with the At utility, do the following:
Step 1. On the command line, type the command at TIME, where TIME is the time when the command is to be executed.

The TIME argument can be defined in any of the following formats:
HH:MM specifies the exact hour and minute; For example, 04:00 specifies 4:00 a.m.
midnight specifies 12:00 a.m.
noon specifies 12:00 p.m.
MONTHDAYYEAR format; For example, august 15 2013 specifies the 15th day of august in the year 2013.

Step 2. In the displayed at> prompt, define the job commands:
Type the command the job should execute and press Enter, repeat the step to provide multiple commands.
Once done, press Ctrl+D on an empty line to save task.

Exercise: Following example this will create a kamal directory on root's Desktop at 12:03 p.m.
Step 1.#at 1203
a1>mkdir /root/Desktop/kamal
at>ctl+d (to save)

To view the list of pending jobs, use the atq command.
Step 2. #atq
You can restrict the access to the at commands using the /etc/at.allow and /etc/at.deny files.
If the file at.allow exists, only users listed in the file are allowed to use at and the at.deny file is ignored.

B-Crontab.
In any operating system, it is possible to create jobs that you want to reoccur. This process, known as job
scheduling, is usually done based on user-defined jobs. For Red Hat, this process is handled by the cron service, which can be used to schedule tasks (also called jobs).

To start working with cron, you first need to look at the two config files that control access to the cron service. These two files are:
1-The /etc/cron.allow file:
 If it exists, only these users are allowed.
 If it doesn’t exist, all users except cron.deny are permitted.
2-The /etc/cron.deny file:
 If it exists and is empty, all users are allowed

You can use the crontab command to create, edit, and delete jobs.
Syntax: crontab [-u user] [option]
Options:
-e Edits the user’s crontab
-l Lists the user’s crontab
-r Deletes the user’s crontab

/etc/crontab file represent scheduled jobs and have the following format:
minute hour day month day of week username command

The following define the time when the job is to be run:
minute any integer from 0 to 59

hour  any value from 0 to 23

day  any value from 1 to 31 (must be a valid day if a month is specified)

month  any value from 1 to 12 (you can also use as jan, feb)

day of week  any value from 0 to 7, (0 or 7 Sunday) (or sun, mon)

username specifies the user under which the jobs are run

command command to be executed

Exercise1:
Step 1. Verify that the cron service is currently running:
# service crond status

Step 2. Also verify that the service is set to start when the system boots:
# chkconfig --list crond

Step 3. #vim /sample_script
#!/bin/bash
# Send a msg to all users on the console
wall “Hello World”

Save the file and set the following permissions:
# chmod 775 /sample_script

Step 4. Set up user1’s crontab:
# crontab -u user1 -e

Step 5. Add the following line:
* * * * * /sample_script
*/2 * * * * /sample_script
 Save the file and quit the editor.

Because we are using * in every field ofter 60 seconds you will see the message ”Hello World” on
your screen. In second line */2 means this will execute ofter every 2 minute.

List the current cron jobs of user01:
# crontab -u user

To remove a user’s crontab jobs, use the following command:
# crontab -u user1 -r1 -l

Configure ACL in RHEL6

ACL is extended set of permissions on files and directories that give advanced security when needed. For example you can set different permission for different user on a single file or directory. Two commands control ACLs: getfacl and setfacl. When you use the ls -l or ll command, a plus sign (+) on the side of the permission indicates ACL permission.

Step 1.  Before you can even use ACLs, however, you need to make sure that the file system has been mounted with the ACL parameter:
# mount | grep acl

If nothing is returned, it means that all currently mounted file systems do not have ACLs set up to be used. To mount the file system with the ACL option use the following command:
# mount –t ext4 -o acl,remount /dev/sda5 /data

Step 2. To verify, you can use the previous command:
# mount | grep acl
/dev/sda5 on /data type ext4 (rw,acl)

Step 3. Add the following line in your /etc/fstab file:
/dev/sda5 /data ext4 defaults,acl 1 2
Save and close the file.

Step 4. To make the changes take effect, you need to remount the file system:
# mount -o remount /data

Step 6. You can now verify that your file system has the ACL option:
# mount | grep -i acl
/dev/sda5 on /data type ext3 (rw,acl)

Exercise: To understand ACL let's look an example.
Step 1. Create a sample file (file1) on which you can test an ACL in the /data/backup directory:
#mkdir /data/backup
# cd /data/backup
#touch file1
Check default permission by using following command.
# getfacl /data/backup

Step 2. Set the test file so that user1 also has access to this file:
# setfacl -m u:user1:rwx /data/backup/file1
Where -m means modify, u means ACL for user, rwx means i want to set read, write and execute permission on user1 for file /data/backup/file1

Step 3. Now check the ACL permissions:
# getfacl /data/backup/file1

# file: file1
# owner: root
# group: root
user::rw-
user:user1:rwx
group::r--
mask::rwx
other::r--
Now login as user1 and try to modify file1 it should be modify.

Step 4. Use the setfacl command again to remove the ACL for user01:
# setfacl -x u:user1 /data/backup/file1
Notice -x is used to remove ACL.

Step 5. Verify that the ACL has been removed:
# getfacl file1
# file: file1
# owner: root
# group: root
user::rwgroup::
r--
mask:r--
other:r--

Step 6. If you have multiple ACLs set up on a single file, you can remove them all with the -b option
# setfacl -b filename

Components of Router

Router components:
To configure and troubleshoot a Cisco internetwork, you need to know the major components of Cisco routers and understand what each one does.

1-Bootstrap Stored in the ROM, It will boot the router and then load the IOS.

2-POST (power-on self-test) Stored in the ROM, the POST is used to check the basic  functionality of the router hardware and determines which interfaces are present.

3-ROM monitor Stored in the ROM, the ROM monitor is used for manufacturing, testing, and troubleshooting.

4-Mini-IOS Called the RXBOOT or bootloader by Cisco, the mini-IOS is a small IOS in ROM that can be used to bring up an interface and load a Cisco IOS into flash memory. The mini-IOS can also perform a few other maintenance operations. Mini-IOS is not present on every router.

5-RAM (random access memory) Used to hold ARP cache, routing tables, software and data structures that allow  the router to function. Running-config is stored in RAM, and most routers loads the IOS from flash into RAM upon boot.

6-ROM (read-only memory) Used to start and maintain the router. Holds the POST and the bootstrap program as well as the mini-IOS.

7-Flash memory Stores the Cisco IOS by default. It is EEPROM (electronically erasable programmable read-only memory) created by Intel.

8-NVRAM (nonvolatile RAM) Used to hold the permanent configuration of router. The configuration register is stored in NVRAM.

9-Configuration register It's a 16 digit hexadecimal configuration file that is used to control how the router boots up. Default value is set to 0x2102, which tells the router to load the IOS from flash memory as well as to load the configuration from NVRAM.

10- IOS Internet-networking Operating System. The kernel of Cisco Router IOS, developed by William Eager.

Now you know the different kinds of router components, you can move to learn Booting process of Router.

The Router Boot Sequence
Every device that uses operating system performs a series of steps, called the boot sequence, to test the hardware and load the necessary software. The router boot sequence consists of the following steps:

Step 1. The router performs a POST. The POST tests the hardware to verify that all components of the device are operational and present. The POST is stored in and run from ROM (read-only memory).

Step 2. The bootstrap then looks for and loads the Cisco IOS software. The bootstrap program is responsible for finding where each IOS program is located and then loading the file. By default, the IOS software is loaded from flash memory in all Cisco routers. The default order of an IOS loading from a router is flash, TFTP server, then ROM.

Step 3. The IOS software looks for a valid configuration file stored in NVRAM. This file is called startup-config.

Step 4. If a startup-config file is in NVRAM, the router will copy this file and place it in RAM and call the file running-config.

Step 5. Finally you will get router user console prompt. Where you can perform all the tasks.

CCNA Dumps Part4

Hi guy's i know you are so much interested in CCNA Certification and i hope this will help you to prepare to became a CCNA certified.

1. On a VLSM network, which mask should you use on point-to-point WAN links in order to reduce the waste of IP addresses?
A. /27
B. /28
C. /29
D. /30
E. /31

2. To test the IP stack on your local host, which IP address would you ping?
A. 127.0.0.0
B. 1.0.0.127
C. 127.0.0.1
D. 127.0.0.255
E. 255.255.255.255

3. What is the only connection type that supports the use of the /30 mask?
A. Point-to-multipoint
B. Point-to-point
C. Multipoint-to-multipoint
D. Host to switch

4. To use VLSM, what capability must the routing protocols in use possess?
A. Support for multicast
B. Multi-protocol support
C. Transmission of subnet mask information
D. Support for unequal load balancing

5. What is another term for route aggregation?
A. VLSM
B. Load balancing
C. Subnetting
D. Summarization

6. Which of the following is a result of route aggregation?
A. Smaller routing tables
B. More complete routing tables
C. Increased memory usage
D. Increased CPU usage

7. The network address used to advertise a summary address is always which of the following?
A. The last network address in the block
B. The next to last network in the block
C. The second network in the block
D. The first network in the block

8. When a ping to the loopback address fails, what can you assume?
A. The IP address of the local host is incorrect.
B. The IP address of the remote host is incorrect.
C. The NIC is not functional.
D. The IP stack has failed to initialize.

9. When a ping to the local host IP address fails, what can you assume?
A. The IP address of the local host is incorrect.
B. The IP address of the remote host is incorrect.
C. The NIC is not functional.
D. The IP stack has failed to initialize.

10. When a ping to the local host IP address succeeds but a ping to the default gateway IP address fails, what can you rule out? (Choose all that apply.)
A. The IP address of the local host is incorrect.
B. The IP address of the gateway is incorrect.
C. The NIC is not functional.
D. The IP stack has failed to initialize.

11. If a remote host can be pinged, what problems can you rule out?
A. The IP address of the local host is incorrect.
B. The IP address of the gateway is incorrect.
C. The NIC is not functional.
D. The IP stack has failed to initialize.
E. All of the above.

12. What network service is the most likely problem if you can ping a computer by IP address but not by name?
A. DNS
B. DHCP
C. ARP
D. ICMP

13. When you issue the ping command, what protocol are you using?
A. DNS
B. DHCP
C. ARP
D. ICMP

14. Which of the following commands displays the networks traversed on a path to a network destination?
A. ping
B. traceroute
C. pingroute
D. pathroute

15. Which of the following commands uses ICMP echo requests and replies?
A. ping
B. traceroute
C. arp
D. tracert

16. What command is the Windows version of the Cisco command that displays the networks traversed on a path to a network destination?
A. ping
B. traceroute
C. arp
D. tracert

17. Which command displays IP-to-MAC-address mappings on a Windows PC?
A. ping
B. traceroute
C. arp -a
D. tracert

18. What command displays the ARP table on a Cisco router?
A. show ip arp
B. traceroute
C. arp -a
D. tracert

19. What switch must be added to the ipconfig command on a PC to verify DNS configuration?
A. /dns
B. -dns
C. /all
D. -all

20. Which of the following is the best summarization of the following networks: 192.168.128.0 through 192.168.159.0
A. 192.168.0.0/24
B. 192.168.128.0/16
C. 192.168.128.0/19
D. 192.168.128.0/20

21. Which mask should you use on point-to-point WAN links in order to reduce the waste of IP addresses?
A. /27
B. /28
C. /29
D. /30
E. /31

22. What is the subnetwork number of a host with an IP address of 172.16.66.0/21?
A. 172.16.36.0
B. 172.16.48.0
C. 172.16.64.0
D. 172.16.0.0

23. You have an interface on a router with the IP address of 192.168.192.10/29. Including the router interface, how many hosts can have IP addresses on the LAN attached to the router interface?
A. 6
B. 8
C. 30
D. 62
E. 126

24. You need to configure a server that is on the subnet 192.168.19.24/29. The router has the first available host address. Which of the following should you assign to the server?
A. 192.168.19.0 255.255.255.0
B. 192.168.19.33 255.255.255.240
C. 192.168.19.26 255.255.255.248
D. 192.168.19.31 255.255.255.248
E. 192.168.19.34 255.255.255.240

25. You have an interface on a router with the IP address of 192.168.192.10/29. What is the broadcast address the hosts will use on this LAN?
A. 192.168.192.15
B. 192.168.192.31
C. 192.168.192.63
D. 192.168.192.127
E. 192.168.192.255

26. You need to subnet a network that has 5 subnets, each with at least 16 hosts. Which classful subnet mask would you use?
A. 255.255.255.192
B. 255.255.255.224
C. 255.255.255.240
D. 255.255.255.248

27. You configure a router interface with the IP address 192.168.10.62 255.255.255.192 and receive the following error:Bad mask /26 for address 192.168.10.62, Why did you receive this error?
A. You typed this mask on a WAN link and that is not allowed.
B. This is not a valid host and subnet mask combination.
C. ip subnet-zero is not enabled on the router.
D. The router does not support IP.

28. If an Ethernet port on a router were assigned an IP address of 172.16.112.1/25, what would be the valid subnet address of this interface?
A. 172.16.112.0
B. 172.16.0.0
C. 172.16.96.0
D. 172.16.255.0
E. 172.16.128.0

29. Using the illustration from the previous question, what would be the IP address of S0 if you were using the first subnet? The network ID is 192.168.10.0/28 and you need to use the last available IP address in the range. Again, the zero subnet should not be considered valid for this question.
A. 192.168.10.24
B. 192.168.10.62
C. 192.168.10.30
D. 192.168.10.127

30. Which configuration command must be in effect to allow the use of 8 subnets if the Class C subnet mask is 255.255.255.224?
A. Router(config)#ip classless
B. Router(config)#ip version 6
C. Router(config)#no ip classful
D. Router(config)#ip unnumbered
E. Router(config)#ip subnet-zero
F. Router(config)#ip all-nets

31. You have a network with a subnet of 172.16.17.0/22. Which is the valid host address?
A. 172.16.17.1 255.255.255.252
B. 172.16.0.1 255.255.240.0
C. 172.16.20.1 255.255.254.0
D. 172.16.16.1 255.255.255.240
E. 172.16.18.255 255.255.252.0
F. 172.16.0.1 255.255.255.0

32. Your router has the following IP address on Ethernet0: 172.16.2.1/23. Which of the following can be valid host IDs on the LAN interface attached to the router? (Choose two.)
A. 172.16.0.5
B. 172.16.1.100
C. 172.16.1.198
D. 172.16.2.255
E. 172.16.3.0
F. 172.16.3.255

33. To test the IP stack on your local host, which IP address would you ping?
A. 127.0.0.0
B. 1.0.0.127
C. 127.0.0.1
D. 127.0.0.255
E. 255.255.255.255

34. Which of the following connection methods available to connect to a router is considered out-of-band?
A. Serial port
B. VTY port
C. HTTP port
D. Aux port

35. Which two of the following commands are required when configuring SSH on your router?
A. enable secret password
B. exec-timeout 0 0
C. ip domain-name name
D. username name password password
E. ip ssh version 2

36. Which command will show you whether a DTE or a DCE cable is plugged into serial 0?
A. sh int s0
B. sh int serial 0
C. show controllers s 0
D. show serial 0 controllers

37. Which of the following is a correct combination of file type and default location in a Cisco router?
A. IOS/NVRAM
B. Startup configuration/flash memory
C. IOS/flash memory
D. Running configuration/NVRAM

38. You set the console password, but when you display the configuration, the password doesn’t show up; it looks like this:
[output cut]
Line console 0
Exec-timeout 1 44
Password 7 09FGH68QR
Login
[output cut]
What command would configure the password to be stored this way?
A. encrypt password
B. service password-encryption
C. service-password-encryption
D. exec-timeout 1 22

39. Which of the following commands will configure all the default VTY ports on a router?
A. Router#line vty 0 4
B. Router(config)#line vty 0 4
C. Router(config-if)#line console 0
D. Router(config)#line vty all

40. Which of the following commands sets the secret password to Kamal?
A. enable secret password Kamal
B. enable secret kamal
C. enable secret Kamal
D. enable password Kamal

41. If you wanted administrators to see a message when logging into the router, which command would you use?
A. message banner motd
B. banner message motd
C. banner motd
D. message motd

42. What command do you type to save the configuration stored in RAM to NVRAM?
A. Router(config)#copy current to starting
B. Router#copy starting to running
C. Router(config)#copy running-config startup-config
D. Router#copy run start

43. You try to telnet into SRouter from router Corp and receive this message:
Corp#telnet SRouter
Trying SRouter (10.0.0.1)…Open
Password required, but none set
[Connection to SRouter closed by foreign host]
Corp#
Which of the following sequences will address this problem correctly?
A. Corp(config)#line console 0
Corp (config-line)#password password
Corp (config-line)#login
B. SRemote(config)#line console 0
Corp (config-line)#enable secret password
Corp (config-line)#login
C. Corp(config)#line vty 0 4
Corp (config-line)#password password
Corp (config-line)#login
D. SRemote(config)#line vty 0 4
Corp (config-line)#password password
Corp (config-line)#login

44. Which command will delete the contents of NVRAM on a router?
A. delete NVRAM
B. delete startup-config
C. erase NVRAM
D. erase start

45. What is the problem with an interface if you type show interface serial 0 and receive the following message?
Serial0 is administratively down, line protocol is down
A. The keepalives are different times.
B. The administrator has the interface shut down.
C. The administrator is pinging from the interface.
D. No cable is attached.

46. Which of the following commands displays the configurable parameters and statistics of all interfaces on a router?
A. show running-config
B. show startup-config
C. show interfaces
D. show versions

47. If you delete the contents of NVRAM and reboot the router, what mode will you be in?
A. Privileged mode
B. Global mode
C. Setup mode
D. NVRAM loaded mode

48. You type the following command into the router and receive the following output:
Router#show serial 0/0
^
% Invalid input detected at '^' marker.
Why was this error message displayed?
A. You need to be in privileged mode.
B. You cannot have a space between serial and 0/0.
C. The router does not have a serial0/0 interface.
D. Part of the command is missing.

49. Which of the following commands will display the current IP addressing and the layer 1 and 2 status of an interface? (Choose two.)
A. show version
B. show interfaces
C. show controllers
D. show ip interface
E. show running-config

50. At which layer of the OSI model would you assume the problem is if you type show interface serial 1 and receive the following message?
Serial1 is down, line protocol is down
A. Physical layer
B. Data Link layer
C. Network layer
D. None; it is a router problem

OK Now it's time to check your answer and get score, if your score is below than 80% i will recommend to retake your test.

1. D. A point-to-point link uses only two hosts. A /30, or 255.255.255.252, mask provides two hosts per subnet.

2. C. To test the local stack on your host, ping the loopback interface of 127.0.0.1.

3. B. The only connection type that supports the use of the /30 mask is point-to-point.

4. C. To use VLSM, the routing protocols in use possess the capability to transmit subnet mask information.

5. D. Another term for route aggregation is summarization.

6. A. Route aggregation results in smaller routing tables.

7. D. The network address used to advertise a summary address is always the first network in the block.

8. D. When a ping to the loopback address fails, you can assume the IP stack has failed to initialize.

9. C. When a ping to the local host IP address fails, you can assume the NIC is not functional.

10. C, D. If a ping to the local host succeeds, you can rule out IP stack or NIC failure.

11. E. If you can ping a remote host, everything is working locally.

12. A. The most likely problem if you can ping a computer by IP address but not by name is a failure of DNS.

13. D. When you issue the ping command, you are using the ICMP protocol.

14. B. The traceroute command displays the networks traversed on a path to a network destination.

15. A. The ping command uses ICMP echo requests and replies.

16. D. tracert is the Windows version of the Cisco command that displays the networks traversed on a path to a network destination.

17. C. The arp -a command displays IP-to-MAC-address mappings on a Windows PC.
18. A. The command that displays the ARP table on a Cisco router is show ip arp.

19. C. The /all switch must be added to the ipconfig command on a PC to verify DNS configuration.
20. C. If you start at 192.168.128.0 and go through 192.168.159.0, you can see this is a block of 32 in the third octet. Since the network address is always the first one in the range, the summary address is 192.168.128.0. What mask provides a block of 32 in the third octet? The answer is 255.255.224.0, or /19

21. D. A point-to-point link uses only two hosts. A /30, or 255.255.255.252, mask provides two hosts per subnet.

22. C. A /21 is 255.255.248.0, which means we have a block size of 8 in the third octet, so we just count by 8 until we reach 66. The subnet in this question is 64.0. The next subnet is 72.0, so the broadcast address of the 64 subnet is 71.255.

23. A. A /29 (255.255.255.248), regardless of the class of address, has only 3 host bits. Six hosts is the maximum number of hosts on this LAN, including the router interface.

24. C. A /29 is 255.255.255.248, which is a block size of 8 in the fourth octet. The subnets are 0, 8, 16, 24, 32, 40, etc. 192.168.19.24 is the 24 subnet, and since 32 is the next subnet, the broadcast address for the 24 subnet is 31. 192.168.19.26 is the only correct answer.

25. A. A /29 (255.255.255.248) has a block size of 8 in the fourth octet. This means the subnets are 0, 8, 16, 24, etc. 10 is in the 8 subnet. The next subnet is 16, so 15 is the broadcast address.

26. B. You need 5 subnets, each with at least 16 hosts. The mask 255.255.255.240 provides 16 subnets with 14 hosts—this will not work. The mask 255.255.255.224 provides 8 subnets, each with 30 hosts. This is the best answer.

27. C. First, you cannot answer this question if you can’t subnet. The 192.168.10.62 with a mask of 255.255.255.192 is a block size of 64 in the fourth octet. The host 192.168.10.62 is in the zero subnet, and the error occurred because ip subnet-zero is not enabled on the router.

28. A. A /25 mask is 255.255.255.128. Used with a Class B network, the third and fourth octets are used for subnetting with a total of 9 subnet bits, 8 bits in the third octet and 1 bit in the fourth octet. Since there is only 1 bit in the fourth octet, the bit is either off or on—which is a value of 0 or 128. The host in the question is in the 0 subnet, which has a broadcast address of 127 since 112.128 is the next subnet.

29. C. A /28 is a 255.255.255.240 mask. The first subnet is 16 (remember that the question stated not to use subnet zero) and the next subnet is 32, so our broadcast address is 31. This makes our host range 17–30. 30 is the last valid host.

30. E. A Class C subnet mask of 255.255.255.224 is 3 bits on and 5 bits off (11100000) and provides 8 subnets, each with 30 hosts. However, if the command ip subnet-zero is not used, then only 6 subnets would be available for use.

31. E. A Class B network ID with a /22 mask is 255.255.252.0, with a block size of 4 in the third octet. The network address in the question is in subnet 172.16.16.0 with a broadcast address of 172.16.19.255. Only option E has the correct subnet mask listed, and 172.16.18.255 is a valid host.

32. D, E. The router’s IP address on the E0 interface is 172.16.2.1/23, which is 255.255.254.0. This makes the third octet a block size of 2. The router’s interface is in the 2.0 subnet, and the broadcast address is 3.255 because the next subnet is 4.0. The valid host range is 2.1 through 3.254. The router is using the first valid host address in the range.

33. C. To test the local stack on your host, ping the loopback interface of 127.0.0.1.

34. D. The auxiliary port can be configured with modem commands so that a modem can be connected to the router. It lets you dial up a remote router and attach to the auxiliary port if the router is down and you need to configure it out-of-band (means out of the network).

35. C, D. To configure SSH on your router, you need to set the username command, the ip domain-name, login local, and the transport input ssh under the VTY lines, and the crypto key command. However, SSH version 2 is not required, but suggested.

36. C. The show controllers serial 0 command will show you whether either a DTE or DCE cable is connected to the interface. If it is a DCE connection, you need to add clocking with the clock rate command.

37. C. The default locations of the files are IOS in flash memory, startup configuration in NVRAM, and running configuration in RAM.

38. B. The command service password-encryption, from global configuration mode, will encrypt the passwords.

39. B. From global configuration mode, use the line vty 0 4 command to set all five default VTY lines.

40. C. The enable secret password is case sensitive, so the second option is wrong. To set the enable secret password, use the enable secret password command from global configuration mode.

41. C. The typical banner is a message of the day (MOTD) and is set by using the global configuration mode command banner motd.

42. D. To copy the running-config to NVRAM so that it will be used if the router is restarted, use the copy running-config startup-config command in privileged mode (copy run start for short).

43. D. To allow a VTY (Telnet) session into your router, you must set the VTY password. Option C is wrong because it is setting the password on the wrong router. Notice that the answers you have to set the password before you set the login command. Remember, Cisco may have you set the password before the login command.

44. D. The erase startup-config command erases the contents of NVRAM and will put you in setup mode if the router is restarted.

45. B. If an interface is shut down, the show interface command will show the interface as administratively down. (It is possible that no cable is attached, but you can’t tell that from this message.)

46. C. With the show interfaces command, you can view the configurable parameters, get statistics for the interfaces on the router, verify if the interfaces are shut down, and see the IP address of each interface.

47. C. If you delete the startup-config and reload the router, the router will automatically enter setup mode. You can also type setup from privileged mode at any time.

48. D. You can view the interface statistics from user mode, but the command is show interface serial 0/0.

49. B, D. The commands show interfaces and show ip interface will show you the layer 1 and 2 status and the IP addresses of your router’s interfaces.

50. A. If you see that a serial interface and the protocol are both down, then you have a Physical layer problem. If you see serial1 is up, line protocol is down, then you are not receiving (Data Link) keepalives from the remote end.

Understanding OSI Model

Overview of Internetworking Models:

When networks first created, computers could typically communicate only with computers from the same manufacturer. For example, companies ran either a complete DECnet based or an IBM based not both together. In the late 1970s, the Open Systems Interconnection (OSI) reference model was created by the International Organization for Standardization (ISO) to resolve this issue.

The OSI model describes how data and network information are communicated from an application on one computer through the network media to an application on another computer, but this process is too much complicated hence OSI reference model breaks this process into layers. it’s a set of guidelines that application developers can use to create and implement applications that run on a network. It also provides a framework for creating and implementing networking standards, and devices.

Advantages of Reference Models:
Advantages of using the OSI layered model include, but are not limited to, the following:
1-It divides the network communication process into smaller and simpler components.
2-It allows multiple-vendor development through standardization of network components.
3-It allows various types of network hardware and software to communicate.
4-It prevents changes in one layer from affecting other layers.

The OSI has seven different layers, divided into two groups (look figure below). The top three layers define how the applications within the end stations will communicate with each other. The bottom four layers define how data is transmitted end to end.

The OSI reference model has the following seven layers:
A-Application layer (layer 7):
Application layer is acting as an interface between the actual application programs. The OSI application layer is responsible for displaying data and images to the user in a human-recognizable format and to interface with the presentation layer layer below it. Examples of applications that utilize the network are:

• Telnet
• FTP
• Instant Message software ( MSN, Yahoo)
• Microsoft Windows File Shares
• Web Browsers (Internet Explorer, Firefox, Google Chrome, Safari etc.)

B-Presentation layer (layer 6):
It presents data to the Application layer and is responsible for data translation and code formatting (for example, EBCDIC to ASCII). By providing translation services, the Presentation layer ensures that data
transferred from the Application layer of one system can be read by the Application layer of another one.
Tasks like data compression, decompression, encryption, and decryption are associated with this layer.

C-Session Layer(layer 5):
The Session layer is responsible for setting up, managing, and terminating sessions between Presentation layer entities. This layer also provides dialog control between devices. It coordinates communication between systems by offering three different modes: simplex, half duplex, and full duplex.

D-Transport Layer(layer 4):
The Transport layer segments and reassembles data into a data stream.  They provide end-to-end data transport services and can establish a logical connection between the sending host and destination host. Some of you are probably familiar with TCP and UDP already. If so, you know that both work at the Transport layer and that TCP is a reliable service and UDP is not.

Some major tasks of Transport layer you should know: 
1-Flow Control
Data integrity is ensured at the Transport layer by maintaining flow control. Flow control prevents a sending host on one side of the connection from overflowing the buffers in the receiving host—an event that can
result in lost data. 
Connection-oriented communications ensure that the following will be achieved:
1-The segments delivered are acknowledged back to the sender upon their reception.
2-Any segments not acknowledged are retransmitted.
3-Segments are sequenced back into their proper order upon arrival at their destination.
4-A manageable data flow is maintained in order to avoid congestion, overloading, and data loss.

In reliable transport operation, The transmitting device first establishes a connection-oriented session with its peer system, which is called three-way handshake. Data is then transferred; when the transfer is finished, a call termination takes place to cut down the virtual circuit.

2-Three-way handshake
1-The first “connection agreement” segment is a request for synchronization.
2-The next segments acknowledge the request and establish connection rules between hosts.
3-The final segment notifies the destination host that the connection agreement has been accepted and Data transfer can now start.

3-Windowing
Ideally, data transmission happens quickly and efficiently as you can imagine so there’s time available after the sender transmits the data segment and before it recieve the acknowledgments from the receiving machine, the sender uses this time gap as an opportunity to transmit more data. The quantity of data segments (in bytes) that the transmitting machine is allowed to send without receiving an acknowledgment for them is called a window.

4-Acknowledgments
Reliable data delivery ensures the integrity of a stream of data sent from one machine to the other .It guarantees that the data won’t be duplicated or lost. This is achieved through something called acknowledgment a technique that requires a receiving machine to communicate with the transmitting source by sending an acknowledgment message back to the sender when it receives data. The sender documents each segment measured in bytes; it then sends and waits for this acknowledgment before sending the next segment round of bytes. When it sends a segment, the transmitting machine starts a timer and retransmits if it expires before an acknowledgment

E-Network Layer(layer 3):
The Network layer manages device addressing, tracks the location of devices on the network, and determines the best path to transfer data.

Do you know how the router works, ok  let me discuss.
1-First, when a packet is received on a router interface.
2-The destination IP address is checked.
3-If the packet isn’t destined for that particular router, it will look up the destination network address in the routing table.
4-If there is entry in routing table router chooses its exit interface, the packet will be sent to that interface to be framed and sent out on the local network.
5-If the router can’t find an entry for the packet’s destination network in the routing table, the router drops the packet.

Two types of packets are used at the Network layer: data and route updates.
Data packets used to transport user data through the internetwork. Protocols used to support data traffic are called routed protocols; examples of routed protocols are IP and IPv6.

Route update packets are used to help build and maintain routing tables on each router. Protocols that send route update packets are called routing protocols; examples are RIP, EIGRP, and OSPF.

F-Data link Layer.(layer 2):
Data Link layer ensure that messages are delivered to the proper device on a LAN using MAC addresses and will convert messages from the Network layer into bits(0,1) for the Physical layer to transmit.The Data Link layer formats the message into pieces, each called a data frame, and adds a header containing the destination and source MAC address.

Data Link layer has two sublayers:
Media Access Control (MAC) 802.3 Defines how packets are placed on the media. Line discipline, error notification (not correction), ordered delivery of frames, and flow control used at this sublayer.

Logical Link Control (LLC) 802.2 Responsible for identifying Network layer protocols and then encapsulating them. The LLC can also provide flow control and sequencing of control bits.

G-Physical Layer(layer 1):
The Physical layer specifies the electrical, mechanical and functional requirements for activating, maintaining, and deactivating a physical link between systems. It sends bits and receives bits. Bits come only in values of 1 or 0.
                                   If there is any query write to us on comment box

CCNA Dumps Part3

In the following section we will look useful CCNA Dumps Part3 that would help you a lot. 

1. Which of the following is not a benefit of reference models such as the OSI model?
A. It allows changes on one layer to affect operations on all other layers as well.
B. It divides the network communication process into smaller and simpler components, thus aiding component development, design, and troubleshooting.
C. It allows multiple-vendor development through standardization of network components.
D. It allows various types of network hardware and software to communicate.

2. Which of the following devices do not operate at all levels of the OSI model?
A. Network management stations (NMSs)
B. Routers
C. Web and application servers
D. Network hosts

3. When an HTTP document must be retrieved from a location other than the local machine, what layer of the OSI model must be accessed first?
A. Presentations
B. Transport
C. Application
D. Network

4. Which layer of the OSI model offers three different modes of communication: simplex, half duplex, and full duplex?
A. Presentation
B. Transport
C. Application
D. Session

5. Which fields are contained within an IEEE Ethernet frame? (Choose two.)
A. Source and destination MAC address
B. Source and destination network address
C. Source and destination MAC address and source and destination network address
D. FCS field

6. Which of the following are unique characteristics of half-duplex Ethernet when compared to full-duplex Ethernet? (Choose two.)
A. Half-duplex Ethernet operates in a shared collision domain.
B. Half-duplex Ethernet operates in a private collision domain.
C. Half-duplex Ethernet has higher effective throughput.
D. Half-duplex Ethernet has lower effective throughput.
E. Half-duplex Ethernet operates in a private broadcast domain.

7. You want to implement a network medium that is not susceptible to EMI. Which type of cabling should you use?
A. Thicknet coax
B. Thinnet coax
C. Category 5 UTP cable
D. Fiber-optic cable

8. Which of the following types of connections can use full duplex? (Choose three.)
A. Hub to hub
B. Switch to switch
C. Host to host
D. Switch to hub
E. Switch to host

9. What type of RJ45 UTP cable is used between switches?
A. Straight-through
B. Crossover cable
C. Crossover with a CSU/DSU
D. Crossover with a router in between the two switches

10. How does a host on an Ethernet LAN know when to transmit after a collision has occurred? (Choose two.)
A. In a CSMA/CD collision domain, multiple stations can successfully transmit data simultaneously.
B. In a CSMA/CD collision domain, stations must wait until the media is not in use before transmitting.
C. You can improve the CSMA/CD network by adding more hubs.
D. After a collision, the station that detected the collision has first priority to resend the lost data.
E. After a collision, all stations run a random backoff algorithm. When the backoff delay period has expired, all stations have equal priority to transmit data.
F. After a collision, all stations involved run an identical backoff algorithm and then synchronize with each other prior to transmitting data.

11. What type of RJ45 UTP cable do you use to connect a PC’s COM port to a router or switch console port?
A. Straight-through
B. Crossover cable
C. Crossover with a CSU/DSU
D. Rolled

12. You have the following binary number: 10110111. What are the decimal and hexadecimal equivalents?
A. 69/0x2102
B. 183/B7
C. 173/A6
D. 83/0xC5

13. Which of the following contention mechanisms is used by Ethernet?
A. Token passing
B. CSMA/CD
C. CSMA/CA
D. Host polling

14. In the operation of CSMA/CD, which host(s) have priority after the expiration of the backoff algorithm?
A. All hosts have equal priority.
B. The two hosts that caused the collision will have equal priority.
C. The host that sent the jam signal after the collision.
D. The host with the highest MAC address.

15. Which of the following is correct?
A. Full-duplex Ethernet uses one pair of wires.
B. Full-duplex Ethernet uses two pairs of wires.
C. Half-duplex Ethernet uses two pairs of wires.
D. Full-duplex Ethernet uses three pairs of wires.

16. Which of the following statements is false with respect to full duplex?
A. There are no collisions in full-duplex mode.
B. A dedicated switch port is required for each full-duplex node.
C. There are few collisions in full-duplex mode.
D. The host network card and the switch port must be capable of operating in full-duplex mode.

17. Which statement is correct with regard to a MAC address?
A. A MAC, or logical, address is a 48-bit (6-byte) address written in a hexadecimal format.
B. A MAC, or hardware, address is a 64-bit (6-byte) address written in a hexadecimal format.
C. A MAC, or hardware, address is a 48-bit (6-byte) address written in a binary format.
D. A MAC, or hardware, address is a 48-bit (6-byte) address written in a hexadecimal format.

18. Which part of a MAC address is called the organizationally unique identifier (OUI)?
A. The first 24 bits, or 3 bytes
B. The first 12 bits, or 3 bytes
C. The first 24 bits, or 6 bytes
D. The first 32 bits, or 3 bytes

19. Which layer of the OSI model is responsible for combining bits into bytes and bytes into frames?
A. Presentation
B. Data Link
C. Application
D. Transport

20. What is the specific term for the unwanted signal interference from adjacent pairs in the cable?
A. EMI
B. RFI
C. Crosstalk
D. Attenuation

21. Which of the following is part of the IEEE 802.3u standard?
A. 100Base2
B. 10Base5
C. 100Base-TX
D. 1000Base-T

22. 10GBase-Long Wavelength is known as which IEEE standard?
A. 802.3F
B. 802.3z
C. 802.3ab
D. 802.3ae

23. 1000Base-T is which IEEE standard?
A. 802.3F
B. 802.3z
C. 802.3ab
D. 802.3ae

24. When making a HyperTerminal connection, what must the bit rate be set to?
A. 2400bps
B. 1200bps
C. 9600bps
D. 6400bps

25. What must happen if a DHCP IP conflict occurs?
A. Proxy ARP will fix the issue.
B. The client uses a gratuitous ARP to fix the issue.
C. The administrator must fix the conflict by hand at the DHCP server.
D. The dhcp server will reassign new IP addresses to both computers.

26. Which of the following allows a router to respond to an ARP request that is intended for a remote host?
A. Gateway DP
B. Reverse ARP (RARP)
C. Proxy ARP
D. Inverse ARP (IARP)
E. Address Resolution Protocol (ARP)

27. You want to implement a mechanism that automates the IP configuration, including IP address, subnet mask, default gateway, and DNS information. Which protocol will you use to accomplish this?
A. SMTP
B. SNMP
C. DHCP
D. ARP

28. What protocol is used to find the hardware address of a local device?
A. RARP
B. ARP
C. IP
D. ICMP
E. BootP

29. Which of the following are layers in the TCP/IP model? (Choose three.)
A. Application
B. Session
C. Transport
D. Internet
E. Data Link
F. Physical

30. Which class of IP address provides a maximum of only 254 host addresses per network ID?
A. Class A
B. Class B
C. Class C
D. Class D
E. Class E

31. Which of the following describe the DHCP Discover message? (Choose two.)
A. It uses FF:FF:FF:FF:FF:FF as a layer-2 broadcast.
B. It uses UDP as the Transport layer protocol.
C. It uses TCP as the Transport layer protocol.
D. It does not use a layer-2 destination address.

32. Which layer-4 protocol is used for a Telnet connection?
A. IP
B. TCP
C. TCP/IP
D. UDP
E. ICMP

33. How does a DHCP client ensure that no other computer has its assigned IP address?
A. Acknowledge receipt of a TCP segment.
B. Ping to its own address to see if a response is detected.
C. Broadcast a Proxy ARP
D. Broadcast a gratuitous ARP
E. Telnet to its own IP address

34. Which of the following services use TCP? (Choose three.)
A. DHCP
B. SMTP
C. SNMP
D. FTP
E. HTTP
F. TFTP

35. Which of the following services use UDP? (Choose three.)
A. DHCP
B. SMTP
C. SNMP
D. FTP
E. HTTP
F. TFTP

36. Which of the following are TCP/IP protocols used at the Application layer of the OSI model? (Choose three.)
A. IP
B. TCP
C. Telnet
D. FTP
E. TFTP

37. If you use either Telnet or FTP, what layer are you using to generate the data?
A. Application
B. Presentation
C. Session
D. Transport

38. The DoD model (also called the TCP/IP stack) has four layers. Which layer of the DoD model is equivalent to the Network layer of the OSI model?
A. Application
B. Host-to-Host
C. Internet
D. Network Access

39. Which two of the following are private IP addresses?
A. 12.0.0.1
B. 168.172.19.39
C. 172.20.14.36
D. 172.33.194.30
E. 192.168.24.43

40. What layer in the TCP/IP stack is equivalent to the Transport layer of the OSI model?
A. Application
B. Host-to-Host
C. Internet
D. Network Access

41. Which statements are true regarding ICMP packets? (Choose two).
A. ICMP guarantees datagram delivery.
B. ICMP can provide hosts with information about network problems.
C. ICMP is encapsulated within IP datagrams.
D. ICMP is encapsulated within UDP datagrams.

42. What is the address range of a Class B network address in binary?
A. 01xxxxxx
B. 0xxxxxxx
C. 10xxxxxx
D. 110xxxxx

43. Which of the following protocols uses both TCP and UDP?
A. FTP
B. SMTP
C. Telnet
D. DNS

44. What is the maximum number of IP addresses that can be assigned to hosts on a local subnet that uses the 255.255.255.224 subnet mask?
A. 14
B. 15
C. 16
D. 30
E. 31
F. 62

45. You have a network that needs 29 subnets while maximizing the number of host addresses available on each subnet. How many bits must you borrow from the host field to provide the correct subnet mask?
A. 2
B. 3
C. 4
D. 5
E. 6
F. 7

47. What is the subnetwork address for a host with the IP address 200.10.5.68/28?
A. 200.10.5.56
B. 200.10.5.32
C. 200.10.5.64
D. 200.10.5.0

48. The network address of 172.16.0.0/19 provides how many subnets and hosts?
A. 7 subnets, 30 hosts each
B. 7 subnets, 2,046 hosts each
C. 7 subnets, 8,190 hosts each
D. 8 subnets, 30 hosts each
E. 8 subnets, 2,046 hosts each
F. 8 subnets, 8,190 hosts each

49. Which two statements describe the IP address 10.16.3.65/23? (Choose two.)
A. The subnet address is 10.16.3.0 255.255.254.0.
B. The lowest host address in the subnet is 10.16.2.1 255.255.254.0.
C. The last valid host address in the subnet is 10.16.2.254 255.255.254.0.
D. The broadcast address of the subnet is 10.16.3.255 255.255.254.0.
E. The network is not subnetted.

50. If a host on a network has the address 172.16.45.14/30, what is the subnetwork this host belongs to?
A. 172.16.45.0
B. 172.16.45.4
C. 172.16.45.8
D. 172.16.45.12
E. 172.16.45.16

Now check your score
1. A. Reference models prevent, rather than allow, changes on one layer to affect operations on other layers as well, so the model doesn’t hamper development.

2. B. Routers operate no higher than layer 3 of the OSI model.

3. C. When an HTTP document must be retrieved from a location other than the local machine, the Application layer must be accessed first.

4. D. The Session layer of the OSI model offers three different modes of communication: simplex, half duplex, and full duplex.

5. A, D. An Ethernet frame has source and destination MAC addresses, an Ether-Type field to identify the Network layer protocol, the data, and the FCS field that holds the answer to the CRC.

6. A, D. Half-duplex Ethernet works in a shared medium or collision domain. Half duplex provides a lower effective throughput than full duplex.

7. D. Fiber-optic cable provides a more secure, long-distance cable that is not susceptible to EMI interference at high speeds.

8. B, C, E. Hubs cannot run full-duplex Ethernet. Full duplex must be used on a point-to-point connection between two devices capable of running full duplex. Switches and hosts can run full duplex between each other, but a hub can never run full duplex.

9. B. To connect two switches together, you would use a RJ45 UTP crossover cable.

10. B, E. Once transmitting stations on an Ethernet segment hear a collision, they send an extended jam signal to ensure that all stations recognize the collision. After the jamming is complete, each sender waits a predetermined amount of time, plus a random time. After both timers expire, they are free to transmit, but they must make sure the media is clear before transmitting and that they all have equal priority.

11. D. To connect to a router or switch console port, you would use an RJ45 UTP rolled cable.

12. B. You must be able to take a binary number and convert it into both decimal and hexadecimal. To convert to decimal, just add up the 1s using their values. The values that are turned on with the binary number of 10110111 are 128 + 32 + 16 + 4 + 2 + 1 = 183. To get the hexadecimal equivalent, you need to break the eight binary digits into nibbles (4 bits), 1011 and 0111. By adding up these values, you get 11 and 7. In hexadecimal, 11 is B, so the answer is 0xB7.

13. B. Ethernet networking uses Carrier Sense Multiple Access with Collision Detection (CSMA/CD), a protocol that helps devices share the bandwidth evenly without having two devices transmit at the same time on the network medium.

14. A. After the expiration of the backoff algorithm, all hosts have equal priority.

15. B. Full-duplex Ethernet uses two pairs of wires.

16. C. There are no collisions in full-duplex mode.

17. D. A MAC, or hardware, address is a 48-bit (6-byte) address written in a hexadecimal format.

18. A. The first 24 bits, or 3 bytes, of a MAC address is called the organizationally unique identifier (OUI).

19. B. The Data Link layer of the OSI model is responsible for combining bits into bytes and bytes into frames.

20. C. The term for the unwanted signal interference from adjacent pairs in the cable is crosstalk.

21. C. IEEE 802.3.u is Fast Ethernet at 100Mbps and covers 100Base-TX, 100BaseT4, and 100Base-FX.

22. D. IEEE 802.3ae is the standard for 10Gbase-SR, -LR, -ER, -SW, -LW, and -E.
23. C. IEEE 802.3ab is the standard for 1Gbps on twisted-pair.

24. C. When making a HyperTerminal connection, the bit rate must be set to 9600bps.

25. C. If a DHCP conflict is detected, either by the server sending a ping and getting a response or by a host using a gratuitous ARP (arp’ing for its own IP address and seeing if a host responds), then the server will hold that address and not use it again until it is fixed by an administrator.

26. C. Proxy ARP can help machines on a subnet reach remote subnets without configuring routing or a default gateway.

27. C. Dynamic Host Configuration Protocol (DHCP) is used to provide IP information to hosts on your network. DHCP can provide a lot of information, but the most common is IP address, subnet mask, default gateway, and DNS information.

28. B. Address Resolution Protocol (ARP) is used to find the hardware address from a known IP address.

29. A, C, D. This seems like a hard question at first because it doesn’t make sense. The listed answers are from the OSI model and the question asked about the TCP/IP protocol stack (DoD model). However, let’s just look for what is wrong. First, the Session layer is not in the TCP/IP model; neither are the Data Link and Physical layers. This leaves us with the Transport layer (Host-to-Host in the DoD model), Internet layer (Network layer in the OSI), and Application layer (Application/Process in the DoD).

30. C. A Class C network address has only 8 bits for defining hosts: 28 – 2 = 254.

31. A, B. A client that sends out a DHCP Discover message in order to receive an IP address sends out a broadcast at both layer 2 and layer 3. The layer-2 broadcast is all Fs in hex, or FF:FF:FF:FF:FF:FF. The layer-3 broadcast is 255.255.255.255, which means any networks and all hosts. DHCP is connectionless, which means it uses User Datagram Protocol (UDP) at the Transport layer, also called the Host-to-Host layer.

32. B. Although Telnet does use TCP and IP (TCP/IP), the question specifically asks about layer 4, and IP works at layer 3. Telnet uses TCP at layer 4.

33. D. To stop possible address conflicts, a DHCP client will use gratuitous ARP (broadcast an ARP request for its own IP address) to see if another host responds.

34. B, D, E. SMTP, FTP, and HTTP use TCP.

35. A, C, F. DHCP, SNMP, and TFTP use UDP. SMTP, FTP, and HTTP use TCP.

36. C, D, E. Telnet, File Transfer Protocol (FTP), and Trivial FTP (TFTP) are all Application layer protocols. IP is a Network layer protocol. Transmission Control Protocol (TCP) is a Transport layer protocol.

37. C. First, you should know easily that only TCP and UDP work at the Transport layer, so now you have a 50/50 shot. However, since the header has sequencing, acknowledgment, and window numbers, the answer can only be TCP.

38. C. The four layers of the DoD model are Application/Process, Host-to-Host, Internet, and Network Access. The Internet layer is equivalent to the Network layer of the OSI model.

39. C, E. Class A private address range is 10.0.0.0 through 10.255.255.255. Class B private address range is 172.16.0.0 through 172.31.255.255, and Class C private address range is 192.168.0.0 through 192.168.255.255.

40. B. The four layers of the TCP/IP stack (also called the DoD model) are Application/Process, Host-to-Host, Internet, and Network Access. The Host-to-Host layer is equivalent to the Transport layer of the OSI model.

42. C. The range of a Class B network address is 128–191. This makes our binary range 10xxxxxx.

43. D. DNS uses TCP for zone exchanges between servers and UDP when a client is trying to resolve a hostname to an IP addres

44. D. A /27 (255.255.255.224) is 3 bits on and 5 bits off. This provides 8 subnets, each with 30 hosts. Does it matter if this mask is used with a Class A, B, or C network address? Not at all. The number of host bits would never change.

45. D. A 240 mask is 4 subnet bits and provides 16 subnets, each with 14 hosts. We need more subnets, so let’s add subnet bits. One more subnet bit would be a 248 mask. This provides 5 subnet bits (32 subnets) with 3 host bits (6 hosts per subnet). This is the best answer.

46. C. This is a pretty simple question. A /28 is 255.255.255.240, which means that our block size is 16 in the fourth octet. 0, 16, 32, 48, 64, 80, etc. The host is in the 64 subnet.

47.C. C. 200.10.5.64

48. F. A CIDR address of /19 is 255.255.224.0. This is a Class B address, so that is only 3 subnet bits, but it provides 13 host bits, or 8 subnets, each with 8,190 hosts.

49. B, D. The mask 255.255.254.0 (/23) used with a Class A address means that there are 15 subnet bits and 9 host bits. The block size in the third octet is 2 (256 – 254). So this makes the subnets in the interesting octet 0, 2, 4, 6, etc., all the way to 254. The host 10.16.3.65 is in the 2.0 subnet. The next subnet is 4.0, so the broadcast address for the 2.0 subnet is 3.255. The valid host addresses are 2.1 through 3.254.

50. D. A /30, regardless of the class of address, has a 252 in the fourth octet. This means we have a block size of 4 and our subnets are 0, 4, 8, 12, 16, etc. Address 14 is obviously in the 12 subnet.

CCNA Dumps Part2

In the following section we will look CCNA Dumps Part2 test yourself and finally get answer with description on bottom side if there is any confusion write to us on comments box.

1. What protocol does PPP use to identify the Network layer protocol?
A. NCP
B. ISDN
C. HDLC
D. LCP

2. Each field in an IPv6 address is how many bits long?
A. 4
B. 16
C. 32
D. 128

3. The RSTP provides which new port role?
A. Disabled
B. Enabled
C. Discarding
D. Forwarding

4. What does the command routerA(config)#line cons 0 allow you to perform next?
A. Set the Telnet password.
B. Shut down the router.
C. Set your console password.
D. Disable console connections.

5. How long is an IPv6 address?
A. 32 bits
B. 128 bytes
C. 64 bits
D. 128 bits

6. What PPP protocol provides for dynamic addressing, authentication, and multilink?
A. NCP
B. HDLC
C. LCP
D. X.25

7. What command will display the line, protocol, DLCI, and LMI information of an interface?
A. sh pvc
B. show interface
C. show frame-relay pvc
D. sho runn

8. Which of the following is the valid host range for the subnet on which the IP address 192.168.168.188 255.255.255.192 resides?
A. 192.168.168.129–190
B. 192.168.168.129–191
C. 192.168.168.128–190
D. 192.168.168.128–192

9. What does the passive command provide to the RIP dynamic routing protocol?
A. Stops an interface from sending or receiving periodic dynamic updates
B. Stops an interface from sending periodic dynamic updates but not from receiving updates
C. Stops the router from receiving any dynamic updates
D. Stops the router from sending any dynamic updates

10. Which protocol does Ping use?
A. TCP
B. ARP
C. ICMP
D. BootP

11. How many collision domains are created when you segment a network with a 12-port switch?
A. 1
B. 2
C. 5
D. 12

12. Which of the following commands will allow you to set your Telnet password on a Cisco router?
A. line telnet 0 4
B. line aux 0 4
C. line vty 0 4
D. line con 0

13. Which router command allows you to view the entire contents of all access lists?
A. show all access-lists
B. show access-lists
C. show ip interface
D. show interface

14. What does a VLAN do?
A. Acts as the fastest port to all servers
B. Provides multiple collision domains on one switch port
C. Breaks up broadcast domains in a layer 2 switch internetwork
D. Provides multiple broadcast domains within a single collision domain

15. If you wanted to delete the configuration stored in NVRAM, what would you type?
A. erase startup
B. erase nvram
C. delete nvram
D. erase running

16. Which protocol is used to send a destination network unknown message back to originating hosts?
A. TCP
B. ARP
C. ICMP
D. BootP

17. Which class of IP address has the most host addresses available by default?
A. A
B. B
C. C
D. A and B

18. How often are BPDUs sent from a layer 2 device?
A. Never
B. Every 2 seconds
C. Every 10 minutes
D. Every 30 seconds

19. Which one of the following is true regarding VLANs?
A. Two VLANs are configured by default on all Cisco switches.
B. VLANs only work if you have a complete Cisco switched internetwork. No off-brand switches are allowed.
C. You should not have more than 10 switches in the same VTP domain.
D. VTP is used to send VLAN information to switches in a configured VTP domain.

20. Which WLAN IEEE specification allows up to 54Mbps at 2.4GHz?
A. A
B. B
C. G
D. N

21. How many broadcast domains are created when you segment a network with a 12-port switch?
A. 1
B. 2
C. 5
D. 12

22. What flavor of Network Address Translation can be used to have one IP address allow many users to connect to the global Internet?
A. NAT
B. Static
C. Dynamic
D. PAT

23. What protocols are used to configure trunking on a switch? (Choose two.)
A. VLAN Trunking Protocol
B. VLAN
C. 802.1Q
D. ISL

24. What is a stub network?
A. A network with more than one exit point
B. A network with more than one exit and entry point
C. A network with only one entry and no exit point
D. A network that has only one entry and exit point

25. Where is a hub specified in the OSI model?
A. Session layer
B. Physical layer
C. Data Link layer
D. Application layer

26. What are the two main types of access control lists (ACLs)? (Choose two.)
A. Standard
B. IEEE
C. Extended
D. Specialized

27. To back up an IOS, what command will you use?
A. backup IOS disk
B. copy ios tftp
C. copy tftp flash
D. copy flash tftp

28. What command is used to create a backup configuration?
A. copy running backup
B. copy running-config startup-config
C. config mem
D. wr mem

29. What is the main reason the OSI model was created?
A. To create a layered model larger than the DoD model
B. So application developers can change only one layer’s protocols at a time
C. So different networks could communicate
D. So Cisco could use the model

30. Which protocol does DHCP use at the Transport layer?
A. IP
B. TCP
C. UDP
D. ARP

31. If your router is facilitating a CSU/DSU, which of the following commands do you need to use to provide the router with a 64000bps serial link?
A. RouterA(config)#bandwidth 64
B. RouterA(config-if)#bandwidth 64000
C. RouterA(config)#clockrate 64000
D. RouterA(config-if)#clock rate 64
E. RouterA(config-if)#clock rate 64000

32. Which command is used to determine if an IP access list is enabled on a particular interface?
A. show access-lists
B. show interface
C. show ip interface
D. show interface access-lists

33. Which command is used to upgrade an IOS on a Cisco router?
A. copy tftp run
B. copy tftp start
C. config net
D. copy tftp flash

34. The Protocol Data Unit Encapsulation (PDU) is completed in which order?
A. Bits, frames, packets, segments, data
B. Data, bits, segments, frames, packets
C. Data, segments, packets, frames, bits
D. Packets, frames, bits, segments, data

35. A receiving host has failed to receive all of the segments that it should acknowledge. What can the host do to improve the reliability of this communication session?
A. Send a different source port number.
B. Restart the virtual circuit.
C. Decrease the sequence number.
D. Decrease the window size.

36. When a station sends a transmission to the MAC address ff:ff:ff:ff:ff:ff, what type of transmission is it?
A. Unicast
B. Multicast
C. Anycast
D. Broadcast

37. Which layer 1 devices can be used to enlarge the area covered by a single LAN segment? (Choose two.)
A. Switch
B. NIC
C. Hub
D. Repeater
E. RJ45 transceiver

38. Segmentation of a data stream happens at which layer of the OSI model?
A. Physical
B. Data Link
C. Network
D. Transport

39. Which of the following describe the main router functions? (Choose four.)
A. Packet switching
B. Collision prevention
C. Packet filtering
D. Broadcast domain enlargement
E. Internetwork communication
F. Broadcast forwarding
G. Path selection

40. Routers operate at layer ___. LAN switches operate at layer ___. Ethernet hubs operate at layer ___. Word processing operates at layer ___.
A. 3, 3, 1, 7
B. 3, 2, 1, none
C. 3, 2, 1, 7
D. 2, 3, 1, 7
E. 3, 3, 2, none

41. When data is encapsulated, which is the correct order?
A. Data, frame, packet, segment, bit
B. Segment, data, packet, frame, bit
C. Data, segment, packet, frame, bit
D. Data, segment, frame, packet, bit

42. Why does the data communication industry use the layered OSI reference model? (Choose two.)
A. It divides the network communication process into smaller and simpler components, thus aiding component development, design, and
troubleshooting.
B. It enables equipment from different vendors to use the same electronic components, thus saving research and development funds.
C. It supports the evolution of multiple competing standards and thus provides business opportunities for equipment manufacturers.
D. It encourages industry standardization by defining what functions occur at each layer of the model.
E. It provides a framework by which changes in functionality in one layer require changes in other layers.

43. What are two purposes for segmentation with a bridge?
A. To add more broadcast domains
B. To create more collision domains
C. To add more bandwidth for users
D. To allow more broadcasts for users

44. Which of the following is not a cause of LAN congestion?
A. Too many hosts in a broadcast domain
B. Adding switches for connectivity to the network
C. Broadcast storms
D. Low bandwidth

45. If a switch has three computers connected to it, with no VLANs present, how many broadcast and collision domains is the switch creating?
A. Three broadcast and one collision
B. Three broadcast and three collision
C. One broadcast and three collision
D. One broadcast and one collision

46. Acknowledgments, sequencing, and flow control are characteristics of which OSI layer?
A. Layer 2
B. Layer 3
C. Layer 4
D. Layer 7

47. Which of the following are types of flow control? (Choose all that apply.)
A. Buffering
B. Cut-through
C. Windowing
D. Congestion avoidance
E. VLANs

48. If a hub has three computers connected to it, how many broadcast and collision domains is the hub creating?
A. Three broadcast and one collision
B. Three broadcast and three collision
C. One broadcast and three collision
D. One broadcast and one collision

49. What is the purpose of flow control?
A. To ensure that data is retransmitted if an acknowledgment is not received
B. To reassemble segments in the correct order at the destination device
C. To provide a means for the receiver to govern the amount of data sent by the sender
D. To regulate the size of each segment

50. Which three statements are true about the operation of a full-duplex Ethernet network?
A. There are no collisions in full-duplex mode.
B. A dedicated switch port is required for each full-duplex node.
C. Ethernet hub ports are preconfigured for full-duplex mode.
D. In a full-duplex environment, the host network card must check for the availability of the network media before transmitting.
E. The host network card and the switch port must be capable of operating in full-duplex mode.

Now check your answers and know how much you have got score:
1. A. Network Control Protocol is used to help identify the Network layer protocol used in the packet.

2. B. Each field in an IPv6 address is 16 bits long. An IPv6 address is a total of 128 bits.

3. C. The port roles used within RSTP include discarding, learning, and forwarding. The difference between 802.1d and RSTP is the discarding role.

4. C. The command line console 0 places you at a prompt where you can then set your console user-mode password.

5. D. An IPv6 address is 128 bits long, whereas an IPv4 address is only 32 bits long.

6. C. Link Control Protocol in the PPP stack provides negotiation of dynamic addressing, authentication, and multilink.

7. B. The show interface command shows the line, protocol, DLCI, and LMI information of an interface.

8. A. 256 – 192 = 64, so 64 is our block size. Just count in increments of 64 to find our subnet: 64 + 64 =    128. 128 + 64 = 192. The subnet is 128, the broadcast address is 191, and the valid host range is the numbers in between, or 129–190.

9. B. The passive command, short for passive-interface, stops regular updates from being sent out an interface. However, the interface can still receive updates.
10. C. ICMP is the protocol at the Network layer that is used to send echo requests and replies.

11. D. Layer 2 switching creates individual collision domains per port.

12. C. The command line vty 0 4 places you in a prompt that will allow you to set or change your Telnet     password.

13. B. To see the contents of all access lists, use the show access-lists command.

14. C. VLANs break up broadcast domains at layer 2.
15. A. The command erase startup-config deletes the configuration stored in NVRAM.

16. C. ICMP is the protocol at the Network layer that is used to send messages back to an originating router.

17. A. Class A addressing provides 24 bits for host addressing.

18. B. Every 2 seconds, BPDUs are sent out from all active bridge ports by default.

19. D. Switches do not propagate VLAN information by default; you must configure the VTP domain for this to occur. VLAN Trunking Protocol (VTP) is used to propagate VLAN information across a trunk link.

20. C. IEEE 802.11bg is in the 2.4GHz range, with a top speed of 54Mbps.

21. A. By default, switches break up collision domains on a per-port basis but are one large broadcast domain.

22. D. Port Address Translation (PAT) allows a one-to-many approach to network address translation.

23. C, D. VTP is not right because it has nothing to do with trunking except that it sends VLAN information  across a trunk link. 802.1Q and ISL encapsulations are used to configure trunking on a port.
24. D. Stub networks have only one connection to an internetwork. Default routes should be set on a stub network or network loops may occur; however, there are exceptions to this rule.

25. B. Hubs regenerate electrical signals, which are specified at the Physical layer.

26. A, C. Standard and extended access control lists (ACLs) are used to configure security on a router.

27. D. The command copy flash tftp will prompt you to back up an existing file in flash to a TFTP host.

28. B. The command to back up the configuration on a router is copy running-config startup-config.

29. C. The primary reason the OSI model was created was so that different networks could interoperate.

30. C. User Datagram Protocol is a connection network service at the Transport layer, and DHCP uses this connectionless service.

31. E. The clock rate command is two words, and the speed of the line is in bps.

32. C. The show ip interface command will show you if any interfaces have an outbound or inbound access list set.

33. D. The copy tftp flash command places a new file in flash memory, which is the default location for the     Cisco IOS in Cisco routers.

34. C. The PDU encapsulation method defines how data is encoded as it goes through each layer of the TCP/IP     model. Data is segmented at the Transport later, packets created at the Network layer, frames at the Data Link layer, and finally, the Physical layer encodes the 1s and 0s into a digital signal.

35. D. A receiving host can control the transmitter by using flow control (TCP uses windowing by default). By decreasing the window size, the receiving host can slow down the transmitting host so the receiving host does not overflow its buffers.

36. D. A transmission to the MAC address ff:ff:ff:ff:ff:ff is a broadcast transmission to all stations.

37. C, D. Not that you really want to enlarge a single collision domain, but a hub (multiport repeater) will     provide this for you.

38. D. The Transport layer receives large data streams from the upper layers and breaks these up into smaller pieces called segments.

39. A, C, E, G. Routers provide packet switching, packet filtering, internetwork communication, and path     selection. Although routers do create or terminate collision domains, this is not the main purpose of a router, so option B is not a correct answer to this question.

40. B. Routers operate at layer 3. LAN switches operate at layer 2. Ethernet hubs operate at layer 1. Word processing applications communicate to the Application layer interface, but do not operate at layer 7, so the answer would be none.

41. C. The encapsulation method is data, segment, packet, frame, bit.

42. A, D. The main advantage of a layered model is that,: It divides the network communication process into smaller and simpler components, thus aiding component development, design, and troubleshooting; it allows multiplevendor development through standardization of network components.

43. A, D. Unlike full duplex, half-duplex Ethernet operates in a shared collision domain, and it has a lower     effective throughput than full duplex.

44. B. Adding switches for connectivity to the network would reduce LAN congestion rather than cause LAN congestion.

45. C. If a switch has three computers connected to it, with no VLANs present, one broadcast and three     collision domains are created.

46. C. A reliable Transport layer connection uses acknowledgments to make sure all data is transmitted and received reliably. A reliable connection is defined by a virtual circuit that uses acknowledgments, sequencing, and flow control, which are characteristics of the Transport layer (layer 4).

47. A, C, D. The common types of flow control are buffering, windowing, and congestion avoidance.

48. D. If a hub has three computers connected to it, one broadcast and one collision domain is created.

49. C. Flow control allows the receiving device to control the transmitter so the receiving device’s buffer does not overflow.

50. A, B, E. Full duplex means you are using both wire pairs simultaneously to send and receive data. You must have a dedicated switch port for each node, which means you will not have collisions. Both the host network card and the switch port must be capable and set to work in full-duplex mode.
               
                                              Click here to go CCNA Dumps Part3