Cisco Router Commands and their Usages

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.

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

Command	Syntax	Description
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.

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

Command	Syntax	Description
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.

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