Ch. 4: Using the Command-Line Interface

Question 1

Command-line interface

Answer 1

An interface that enables the user to interact with the operating system by entering commands and optional arguments.

Question 2

Telnet

Answer 2

The standard terminal-emulation application layer protocol in the TCP/IP protocol stack. Telnet is used for remote terminal connection, enabling users to log in to remote systems and use resources as if they were connected to a local system. Telnet is defined in RFC 854.

Question 3

Secure Shell (SSH)

Answer 3

A TCP/IP application layer protocol that supports terminal emulation between a client and server, using dynamic key exchange and encryption to keep the communications private.

Question 4

enable mode

Answer 4

A part of the Cisco IOS CLI in which the user can use the most powerful and potentially disruptive commands on a router or switch, including the ability to then reach configuration mode and reconfigure the router.

Question 5

user mode

Answer 5

A mode of the user interface to a router or switch in which the user can type only nondisruptive EXEC commands, generally just to look at the current status, but not to change any operational settings.

Question 6

configuration mode

Answer 6

A part of the Cisco IOS Software CLI in which the user can type configuration commands that are then added to the device’s currently used configuration file (running-config).

Question 7

startup-config file

Answer 7

In Cisco IOS switches and routers, the name of the file that resides in NVRAM memory, holding the device’s configuration that will be loaded into RAM as the running-config file when the device is next reloaded or powered on.

Question 8

running-config file

Answer 8

In Cisco IOS switches and routers, the name of the file that resides in RAM, holding the device’s currently used configuration.

Question 9

line console 0

Answer 9

Global command that changes the context to console configuration mode.

Question 10

login

Answer 10

Line (console and vty) configuration mode. Tells IOS to prompt for a password (no username).

Question 11

password (pass-value)

Answer 11

Line (console and vty) configuration mode. Sets the password required on that line for login if the login command (with no other parameters) is also configured.

Question 12

interface (type port-number)

Answer 12

Global command that changes the context to interface mode—for example, interface FastEthernet 0/1.

Question 13

hostname (name)

Answer 13

Global command that sets this switch’s hostname, which is also used as the first part of the switch’s command prompt.

Question 14

exit

Answer 14

Moves back to the next higher mode in configuration mode.

Question 15

end

Answer 15

Exits configuration mode and goes back to enable mode from any of the configuration submodes.

Question 16

Ctrl+Z

Answer 16

This is not a command, but rather a two-key combination that together do the same thing as the end command.

Question 17

no debug all / undebug all

Answer 17

Enable mode EXEC command to disable all currently enabled debugs.

Question 18

reload

Answer 18

Enable mode EXEC command that reboots the switch or router.

Question 19

copy running-config startup-config

Answer 19

Enable mode EXEC command that saves the active config, replacing the startup-config file used when the switch initializes.

Question 20

copy startup-config running-config

Answer 20

Enable mode EXEC command that merges the startup-config file with the currently active config file in RAM.

Question 21

show running-config

Answer 21

Lists the contents of the running-config file.

Question 22

write erase

erase startup-config

erase nvram:

Answer 22

These enable mode EXEC commands erase the startup-config file.

Question 23

quit

Answer 23

EXEC command that disconnects the user from the CLI session.

Question 24

show startup-config

Answer 24

Lists the contents of the startup-config (initial config) file.

Question 25

enable

Answer 25

Moves the user from user mode to enable (privileged) mode and prompts for a password if one is configured.

Question 26

disable

Answer 26

Moves the user from enable mode to user mode.

Question 27

configure terminal

Answer 27

Enable mode command that moves the user into configuration mode.