Other Useful administrative commands

no ip domain-lookup

Router(config)#no ip domain-lookup 

Ever type in a command incorrectly and are left having to wait for a minute or two as the router tries to translate your command to a domain server of 255.255.255.255? The router is set by default to try to resolve any word that is not a command to a Domain Name System (DNS) server at address 255.255.255.255. If you are not going to set up DNS, turn off this feature to save you time as you type, especially if you are not good in typing.

logging synchronous

Router(config)#line console 0 Router(config-line)#logging synchronous Router(config-line)#exit Router(config)# 

Some time it happens that you are typing a command and an informational line appears in the middle of what you were typing? Lose your place? Do not know where you are in the command, so you just press R and start all over? The logging synchronous command tells the router that if any informational items get displayed on the screen, your prompt and command line should be moved to a new line, so as not to confuse you. The informational line does not get inserted into the middle of the command you are trying to type. If you were to continue typing, the command would execute properly, even though it looks wrong on the screen.

exec-timeout

Router(config)#line console 0 Router(config-line)#exec-timeout 0 0 Router(config-line)# 

The command exec-timeout 0 0 is great for a lab environment because the console never logs out. This is considered to be bad security and is dangerous in the real world. The default for the exec-timeout command is 10 minutes and zero (0) seconds (exec-timeout 10 0).

erase startup-config

Router#erase startup-config 

Some time you want to reconfigure the router. Or want to sell the old one. In such a scenario you would like to erase the start up configuration. The running configuration is still in dynamic memory. Reload the router to clear the running configuration.

do Command

Router(config)#do show running-config 

The do command is useful when you want to execute EXEC commands, such as show, clear, or debug, while remaining in global configuration mode or in any configuration submode. You cannot use the do command to execute the configure terminal command because it is the configure terminal command that changes the mode to global configuration mode

Summary of Useful commands for administrations

Router(config)#boot system flash imagename	Loads the Cisco IOS Software with image-name
Router(config)#boot system tftp image-name 172.16.10.3	Loads the Cisco IOS Software with image-name from a TFTP server
Router(config)#boot system rom	Loads the Cisco IOS Software from ROM.
Router(config)#exit	exit from global configurations
Router#copy running-config startup-config	Saves the running configuration to NVRAM. The router will execute commands in their order on the next reload.
Router#copy running-config startup-config	Saves the running configuration from DRAM to NVRAM (locally).
Router#copy running-config tftp	Copies the running configuration to the remote TFTP server
Address or name of remote host[ ]? 192.168.1.20	The IP address of the TFTP server. Press Enter key
Destination Filename [Router-confg]?	The name to use for the file saved on the TFTP server Press Enter key
!!!!!!!!!!!!!!!	Each bang symbol (!) = 1 datagram of data.
624 bytes copied in 7.05 secs
Router#	File has been transferred successfully
Router#copy tftp running-config	Copies the configuration file from the TFTP server to DRAM.
Address or name of remote host[ ]? 192.168.119.20	The IP address of the TFTP server.
Source filename [ ]?Router-confg	Enter the name of the file you want to retrieve
Destination filename [running-config]?	Press Enter key
Router#	File has been transferred successfully.
Router#copy flash tftp	Backup of flash to tftp
Router#copy tftp flash	Restore flash from tftp server