CCNA Certification/Appendix B - Cisco Router Commands and their Usages

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 CCNA Certification 

AcknowledgementsIntroductionThe OSI ModelApplication LayerTransport LayerNetwork LayerAddressingRouting ProtocolsData Link LayerSwitchingPhysical LayerRouter OperationAdvanced Addressing TopicsAdvanced Routing TopicsAdvanced Switching TopicsSecurityWANConfigurationConclusionReferencesAbout the ExamCisco Router CommandsQuick Reference Sheet

Cisco Router Commands and their Usages[edit]

User Mode Commands[edit]

These commands can only be entered from user mode.

Command Syntax Description
SHOW show ? This is used to view the available commands set to this layer, use this to learn and navigate the Router/Switch.
OSPF show ip ospf nei This is used from the basic user prompt to view neighbor details for WAN connection. To view details, use the "det" after the original command. This is a very helpful trouble shooting command for user level access.

Privileged Mode Commands[edit]

These commands can only be entered from privileged mode. To enter privileged mode, use the enable command.

Command Syntax Descrition
enable enable Switches to privileged mode. If the enable password has been set, you will be prompted to enter it.
disable disable changes to user mode
configure terminal conf[igure] t[erminal] switches to config mode, this will allow you to make critical changes to the Router/Switch
terminal editing terminal editing enabled special unix-style editing commands
show show ? This is used to help the enabled user see the available commands on that specific layer. You may use this on each layer and after any command to help view the next part of syntax.
show sh? This will show options of what is available to you that has "sho" for the beginning of a command, in this case it will have "show" as it's only option. Try using other letters or beginnings to see more variety such as: "s?" or "a?" These will give you a larger list.
cdp show cdp nei det this will show all used connections to your ports and whom they are connected to. This is very helpful when drawing out a system diagram.

Config Commands[edit]

These commands can only be entered from config mode. To enter config mode, use the "conf t" command.

Command Syntax Descrition
Enable enable secret Justin This will set a Password to get to enable mode so others cannot make changes with out proper access. In this case we are making the password Justin (case sensitive).
config-register config-register 0xnnnn This command modifies the boot settings on the router.

Example settings are:

  • 0x2100 - ROM Monitor
  • 0x2101 - ROM Boot
  • 0x2102 - Boot from NVRAM (default)
  • 0x2142 - Boot from NVRAM but ignore startup-config file
hostname hostname NAME changes the router name to NAME
router rip router rip enables the RIP routing protocol and switches to router configuration mode
int int s0 Switches to interface configuration mode (s0 stands for Serial 0 but interfaces naming may vary). It is possible to use other interfaces such as Consoles (local), vty 0 ? (telnet), and much more.. You may also create passwords within those layers for more security using the "password" command at that interfaces layer.

References[edit]