Configuring Router:

A router can be configured in many ways. It might be connected to PC using a rollover cable and Console Port of the router. It is the most basic way in which no initial setup is necessary. The AUX port can also be used to configure. The telnet or SSH can also be used to configure although they need initial configuration.

The CISCO router has several modes like
User Exec Mode: Only permits to use the router.
Privileged Exec Mode: It allows to see the router configuration
Global Configuration Mode: Used to configure parameters used in all over the router
Specific Configuration Mode: Used for specific part configuration.

Some useful routing Codes:

Go to Privilege exec mode:
Router>enable
Router#

Go to configure mode:
Router# configure terminal
Router(config)#

Give hostname:
Router(config)# hostname {name}
name(config)#

Give password:
Router(config)# enable password {password}
Router(config)# enable secret {password} // Encrypted password

Create username and password:
Router(config)# username {name} password {ps}
Router(config)# line console 0
Router(config)# no password
Router(config)# login local

Set console password:
Router(config)# line console 0
Router(config-line)# password {password}
Router(config-line)# login

Set vty password (Telnet):
Router(config)# line vty {start port} {end port}
Router(config-line)# password {ps}
Router(config-line)# login

Set ip address to fast-ethernet ports:
Router(config)# interface fa 0/0
Router(config-if)# ip address {ip} {subnet mask}
Router(config-if)# no shutdown