Cisco Systems 78-11741-02 manual Using the no and default Forms of Commands, Xliii

Using Cisco IOS Software

Using the no and default Forms of Commands

Table 2 How to Find Command Options (continued)

Command		Comment
Router(config-if)# ip address ?		Enter the command that you want to
A.B.C.D	IP address	configure for the interface. This
negotiated	IP Address negotiated over PPP	example uses the ip address command.
Router(config-if)# ip address
		Enter ? to display what you must enter
		next on the command line. In this
		example, you must enter an IP address
		or the negotiated keyword.
		A carriage return (<cr>) is not
		displayed; therefore, you must enter
		additional keywords or arguments to
		complete the command.
Router(config-if)#ip address 172.16.0.1 ?		Enter the keyword or argument you
A.B.C.D	IP subnet mask	want to use. This example uses the
Router(config-if)#ip address 172.16.0.1		172.16.0.1 IP address.
		Enter ? to display what you must enter
		next on the command line. In this
		example, you must enter an IP subnet
		mask.
		A <cr> is not displayed; therefore, you
		must enter additional keywords or
		arguments to complete the command.
Router(config-if)#ip address 172.16.0.1 255.255.255.0 ?		Enter the IP subnet mask. This example
secondary	Make this IP address a secondary address	uses the 255.255.255.0 IP subnet mask.
<cr>		Enter ? to display what you must enter
Router(config-if)#ip address 172.16.0.1 255.255.255.0
		next on the command line. In this
		example, you can enter the secondary
		keyword, or you can press Enter.
		A <cr> is displayed; you can press
		Enter to complete the command, or
		you can enter another keyword.
Router(config-if)#ip address 172.16.0.1 255.255.255.0		In this example, Enter is pressed to
Router(config-if)#		complete the command.

Using the no and default Forms of Commands

Almost every configuration command has a no form. In general, use the no form to disable a function. Use the command without the no keyword to reenable a disabled function or to enable a function that is disabled by default. For example, IP routing is enabled by default. To disable IP routing, use the no ip routing command; to reenable IP routing, use the ip routing command. The Cisco IOS software command reference publications provide the complete syntax for the configuration commands and describe what the no form of a command does.

Configuration commands also can have a default form, which returns the command settings to the default values. Most commands are disabled by default, so in such cases using the default form has the same result as using the no form of the command. However, some commands are enabled by default and

Cisco IOS IP Configuration Guide

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