CCNA Chapter 2

• Shell - The user interface that allows users to request specific tasks from the computers. These requests can be made either through the CLI or GUI interfaces.
• Kernel - Communicates between the hardware and software of a computer and manages how hardware resources are used to meet software requirements.
• Hardware - The physical part of a computer including underlying electronics.
• A GUI allows the user to interact with the system using an environment of graphical icons, menus, and windows.

  A GUI is more user-friendly and requires less knowledge of the underlying command structure that controls the system.
• PC operating system enables a user to do the following:

  • Use a mouse to make selections and run programs
  • Enter text and text-based commands
• CLI-based network operating system enables a network technician to do the following:

  • Use a keyboard to run CLI-based network programs
  • Use a keyboard to enter text and text-based commands
  • View output on a monitor
• Console - A physical management port used to access a device in order to provide maintenance, such as performing the intial configurations.
• Secure Shell (SSH) - Establishes a secure remote CLI connection to a device, through a virtual interface, over a network.
• Telnet - Establishes an insecure remote CLI connection to a device over the network.
• Terminal emulation programs are used to connect to a network device by either a console port or by an SSH/Telnet connection.
• What are the two primary command modes:

  • User EXEC Mode
  • Privileged EXEC Mode
• User EXEC Mode allows access to only a limited number of basic monitoring commands.

  Identified by the CLI prompt that ends with the > symbol.
• Privileged EXEC Mode allows access to all commands and features.

  Identified by the CLI prompt that ends with the # symbol.
• Privileged EXEC Mode:

  
  

  To move from user EXEC to Privileged EXEC Mode, use the enable command.
• Global Configuration Mode:

  
  

  To move in and out of global configuration mode, use the configure terminal command.

  
  

  To return to Privilege EXEC Mode, use the exit command.
• Line Configuration Mode:

  
  

  To move in and out of line configuration mode, use the line command followed by the management line type.

  
  

  To return to global configuration mode, use the exit command.
• Subconfiguration Modes:

  To move out of any subconfiguration mode to get back to global configuration mode, use the exit command.

  
  

  To return to Privilege EXEC Mode, use the end command or key combination Ctrl + Z.
• To move directly from one subconfiguration mode to another, type in the desired subconfiguration mode command.
• Global Configuration Mode used to access configuration options on the device.
• Line Configuration Mode used to configure console, SSH, Telnet or AUX access.
• Interface Configuration Mode used to configure a switch port or router interface
• Basic IOS Command Structure

  A) Prompt

  B) Command

  C) Space

  D) Key or Argument

  
• Keyword - This is specific parameter defined in the operating system.
• Argument - This is not predefined; it is a value or variable defined by the user.
• The IOS has two forms of help available:

  • Context-sensitive help enables you to find answer quickly.
  • Command syntax check verifies that a valid command was entered by the user.
• The command syntax provides the pattern, or format, that must be used when entering a command.
• True or False. The first configuration command on any device should be to give it a unique hostname.

  True
• True or False. All devices are assigned a factory default name.

  True
• Guidelines for naming devices:

  • Start with a letter
  • Contain no spaces
  • End with a letter or digit
  • Use only letters, digits, and dashes
  • Be less than 64 characters in length
• True or False. The use of weak or easily guessed passwords are a security concern.

  True
• Password Guidelines:

  • Use passwords that are more than eight characters in length.
  • Use a combination of upper and lowercase letters, numbers, special characters, and/or numeric sequences.
  • Avoid using the same password for all devices.
  • Do not use common words because they are easily guessed.
• Securing user EXEC mode access:

  1. line console 0
  2. password
  3. login
• Securing privileged EXEC mode access:

  1. Enter global configuration mode.
  2. enable secret
• Securing VTY line access:

  1. line vty 0 15
  2. password
  3. login
• Encrypt Passwords

  • To encrypt all plaintext passwords, use the service password-encryption global config command.

  • Use the show running-config command to verify that the passwords on the device are now encrypted.
• A banner message is important to warn unauthorized personnel from attempting to access the device.

  To create a banner message of the day on a network device, use the banner motd # the message of the day # global config command.
• The # in the command syntax is called the delimiting character. It is entered before and after the message.
• There are two system files that store the device configuration:

  • startup-config - This is the saved configuration file that is stored in NVRAM
  • running-config - This is stored in Random Access Memory (RAM).
• To save changes made to the running configuration to the startup configuration file, use the copy running-config startup-config privileged EXEC mode command.
• The use of IP addresses is the primary means of enabling devices to locate one another and establish end-to-end communication on the internet.