Chapter 4 - Using the Command-Line Interface Flashcards
What is a CLI?
A CLI (Command Line Interface) is a text based interface in which the user enters text commands that are sent to the switch to tell it what to do.
What is the name of the Cisco switch’s operating system?
IOS (Internetwork Operating System)
What is a Rollover Cable pinout?
A cable specifically designed to create an interface with a device. They are used to connect a PC to the console port of a networking device (e.g. Router, Switch). The pinout looks like:
1 to 8
2 to 7
3 to 6
4 to 5
What are the parameters of the terminal emulator software that Cisco uses?
The below must be configured on the PCs serial port to match the switch’s console port settings
- Baud Rate - 9600 bits per second
- Flow Control - No hardware flow control
- Data Bits - 8-bit ASCII
- Parity - No parity bits
- Stop Bits - 1 stop bit
The last 3 parameters are collectively known as 8N1.
Describe Telnet
Telnet is an Application layer protocol that is used to connect to the CLI of a device using its IP. A Telnet client (the terminal application on the user’s side) accepts keyboard inputs and sends the inputted commands to a Telnet server (the switch). The server then accepts the inputted text, interprets it as a command, and replies back.Telnet is insecure as it is unencrypted (sends all text including username and passwords as plain text).
Descibe SSH
SSH (Secure Shell) has the same basic concept as Telnet in that you use the client terminal to connect to a Switch’s CLI via IP and input commands, however unlike Telnet it is secure. SSH encrypts all of its packets.
What are the three CLI access methods for Cisco?
- SSH
- Telnet
- Console
What is user EXEC mode?
User EXEC mode is the default mode that users are put into when connecting to a CLI using any of the three methods. User EXEC mode allows the user to look around without being able to change anything. If a command is inputted the device will describe the outcome of this command but won’t make changes to the switch.
What is Enable/Privileged EXEC mode?
Enable mode/privileged mode/privileged EXEC mode can be accessed using the enable command which moves the user from user EXEC mode to enable mode. In this mode, commands can be executed and you will actually see the outcome happen although this mode doesn’t allow you to make changes to the switch’s configuration. (E.g. entering the reload command from this mode will reboot Cisco IOS).
How can you tell which mode you are in?
If the command prompt lists the hostname followed by a > then you are in user mode.
If the command prompt lists the hostname followed by a # then you are in enable mode.
If the command prompt lists the hostname followed by (config)# then you are in configuration mode.
How do you connect to a Cisco Switch by default?
By default you can only connect to a Cisco switch via the console, Telnet and SSH must be enabled from within the switch. The console doesn’t require a password by default as Cisco assumes that if you can connect to the console then you should have access to the switch anyway as you have to plug in physically. You have the option to set a password when you first connect via console or when you first switch to enable mode.
What is the Configuration mode?
Commands entered in configuration mode will update the active configuration of the switch. These changes take place immediately after the enter key is pressed on the command. You can only move to configuration mode from enable mode and you can only move from configuration mode to enable mode.
What are Configuration Submodes?
Each submode tells the switch the topic about which you will be entering the next few configuration commands. (E.g Interface is a common submode so entering ‘interface FastEthernet 0/1’ would allow the user to configure this interface specifically).
What forms of memory does Cisco use and what are their purposes?
- RAM - Sometimes called DRAM (Dynamic RAM) is used for working storage. The active configuration file is stored here. As is IOS while it is in use.
- Flash Memory - Either a chip inside the switch or a removable memory card, flash memory stores Cisco IOS images and is where Cisco IOS is retrieved from on boot. It can also be used to store other files (E.g. backups and configuration files.
- ROM - Stores a bootstrap program that is loaded when the switch first powers on. This program finds the Cisco IOS image and manages the process of loading Cisco IOS into RAM where Cisco IOS then takes over operation of the switch.
- NVRAM - Nonvolatile RAM stores the startup configuration file that is used when the switch is first powered on and when the switch is reloaded. The running config needs to be copied into this in order to be saved or it will be erased when the switch shuts down (copy running-config startup-config).
What are the two different configuration files that Cisco switches use?
startup-config - Stored in NVRAM, contains the initial configuration used anytime the switch reloads Cisco IOS. The running config needs to be copied into this in order to be saved or it will be erased when the switch shuts down (copy running-config startup-config).
running-config - Stored in RAM, contains the currently used configuration commands. This file changes dynamically as and when a user enters commands in configuration mode.
