New CCNA – IOS Questions

Note: If you are not sure about Cisco IOS, please read our Cisco Router Boot Sequence Tutorial and Cisco Command Line Interface CLI.

Question 1

Which command encrypts all plaintext passwords?

A. Router# service password-encryption
B. Router(config)# password-encryption
C. Router(config)# service password-encryption
D. Router# password-encryption

 

Answer: C

Question 2

What can be done to secure the virtual terminal interfaces on a router? (Choose two)

A. Administratively shut down the interface.
B. Physically secure the interface.
C. Create an access list and apply it to the virtual terminal interfaces with the access-group command.
D. Configure a virtual terminal password and login process.
E. Enter an access list and apply it to the virtual terminal interfaces using the access-class command.

 

Answer: D E

Explanation

It is a waste to administratively shut down the interface. Moreover, someone can still access the virtual terminal interfaces via other interfaces -> A is not correct.

We can not physically secure a virtual interface because it is “virtual” -> B is not correct.

To apply an access list to a virtual terminal interface we must use the “access-class” command. The “access-group” command is only used to apply an access list to a physical interface -> C is not correct; E is correct.

The most simple way to secure the virtual terminal interface is to configure a username & password to prevent unauthorized login -> D is correct.

Question 3

Refer to the exhibit. Why is flash memory erased prior to upgrading the IOS image from the TFTP server?

Router# copy tftp flash Address or name of remote host []? 192.168.2.167 Source filename []? c1600-k8sy-mz.123-16a.bin Destination filename [c1600-k8sy-mz.123-16a.bin]? Accessing tftp://192.168.2.167/ c1600-k8sy-mz.l23-16a.bin… Erasing flash before copying? [confirm] Erasing the flash filesystem will remove all files! continue? [confirm] Erasing device Eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee Eeeeeeeeeeeeeeeeeeeeeeeeeeeeeee …erased Erase of flash: complete Loading c1600-k8sy-mz.l23-16a.bin from 192.168.2.167 (via Ethernet0): !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! [OK - 6888962/13777920 bytes] verifying checksum… OK (0x7BF3) 6888962 bytes copied in 209.920 secs (32961 bytes/sec) Router#

A. The router cannot verify that the Cisco IOS image currently in flash is valid
B. Flash memory on Cisco routers can contain only a single IOS image.
C. Erasing current flash content is requested during the copy dialog.
D. In order for the router to use the new image as the default, it must be the only IOS image in flash.

 

Answer: C

Explanation

During the copy process, the router asked “Erasing flash before copying? [confirm]” and the administrator confirmed (by pressing Enter) so the flash was deleted.

Note: In this case, the flash has enough space to copy a new IOS without deleting the current one. The current IOS is deleted just because the administrator wants to do so. If the flash does not have enough space you will see an error message like this:

%Error copying tftp://192.168.2.167/ c1600-k8sy-mz.l23-16a.bin (Not enough space on device)

Question 4

How does using the service password encryption command on a router provide additional security?

A. by encrypting all passwords passing through the router
B. by encrypting passwords in the plain text configuration file
C. by requiring entry of encrypted passwords for access to the device
D. by configuring an MD5 encrypted key to be used by routing protocols to validate routing exchanges
E. by automatically suggesting encrypted passwords for use in configuring the router

 

Answer: B

Explanation

By using this command, all the (current and future) passwords are encrypted. This command is primarily useful for keeping unauthorized individuals from viewing your password in your configuration file.

Question 5

What is a global command?

A. a command that is available in every release of IOS, regardless of the version or deployment status
B. a command that can be entered in any configuration mode
C. a command that is universal in application and supports all protocols
D. a command that is implemented in all foreign and domestic IOS versions
E. a command that is set once and affects the entire router

 

Answer: E

Explanation

A global command is a command in this form:

Device(config)#

This mode can affect the entire router/switch.

For more information about modes in Cisco devices, please read my Cisco Command Line Interface CLI tutorial.

Question 6

Refer to the exhibit.

line vty 0 4 password 7 030752180599 login transport input ssh

What is the effect of the configuration that is shown?
A. It configures SSH globally for all logins.
B. It tells the router or switch to try to establish an SSh connection first and if that foils to use Telnet.
C. It configures the virtual terminal lines with the password 030752180500.
D. It configures a Cisco network device to use the SSH protocol on incoming communications via the virtual terminal ports.
E. It allows seven failed login attempts before the VTY lines are temporarily shutdown.

 

Answer: D

Question 7

Which router IOS commands can be used to troubleshoot LAN connectivity problems? (Choose three)

A. ping
B. tracert
C. ipconfig
D. show ip route
E. winipcfg
F. show interfaces

 

Answer: A D F

Explanation

The ping command can be used to test if the local device can reach a specific destination -> A is correct.

“tracert” is not a valid command in Cisco IOS commands, the correct command should be “traceroute” -> B is not correct.

The ipconfig command is not a valid command in Cisco IOS too -> C is not correct.

The “show ip route” command can be used to view the routing table of the router. It is a very useful command to find out many connectivity problems (like directly connected networks, learned network via routing protocols…) -> D is correct.

“winipcfg” is an old tool in Windows 95/98 to view IP settings of the installed network interfaces. But it is not a valid command in Cisco IOS commands -> E is not correct.

The “show interfaces” command is used to check all the interfaces on the local device only. It has very limited information to trouble LAN connectivity problem but it is the most reasonable to choose -> F is acceptable.

Question 8

Which command shows your active Telnet connections?

A. show sessions
B. show cdp neighbors
C. show users
D. show queue

 

Answer: A

Question 9

Which command would you configure globally on a Cisco router that would allow you to view directly connected Cisco devices?

A. enable cdp
B. cdp enable
C. cdp run
D. run cdp

 

Answer: C

Question 10

A network administrator needs to allow only one Telnet connection to a router. For anyone viewing the confguration and issuing the show run command, the password for Telnet access should be encrypted. Which set of commands will accomplish this task?

A. service password-encryption
access-list 1 permit 192.168.1.0 0.0.0.255
line vty 0 4
login
password cisco
access-class 1

B. enable password secret
line vty 0
login
password cisco

C. service password-encryption
line vty 1
login
password cisco

D. service password-encryption
line vty 0 4
login
password cisco

 

Answer: C

Question 11

What is the effect of using the service password-encryption command?

A. Only passwords configured after the command has been entered will be encrypted.
B. Only the enable password will be encrypted.
C. Only the enable secret password will be encrypted
D. It will encrypt the secret password and remove the enable secret password from the configuration.
E. It will encrypt all current and future passwords.

 

Answer: E

Explanation

The secret password (configured by the command “enable secret “) is always encrypted even if the “service password-encryption” command is not used. Moreover, the secret password is not removed from the configuration with this command, we still see it in encrypted form in the running-config -> D is not correct.

The “enable password ” does not encrypt the password and can be viewed in clear text in the running-config. By using the “service password-encryption” command, that password is encrypted (both current and future passwords) -> A is not correct, E is correct.

Answer B – Only the enable password will be encrypted seems to be correct but it implies the secret password will not be encrypted and stay in clear text, which is not correct.

For your information, the secret password is encrypted with MD5 one-way hash algorithm which is harder to break than the encryption algorithm used by the “service password-encryption” command.