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Command Reference
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Release 12.0(1)T
option
To configure Cisco IOS Dynamic Host Configuration Protocol (DHCP) Server options, use the
option DHCP pool configuration command. Use the no form of this command to remove the
options.
option code [instance number] {ascii string | hex string | ip address}
no option code [instance number]
Syntax Description
Defaults
The default instance number is 0.
Command Modes
DHCP pool configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 12.0(1)T.
DHCP provides a framework for passing configuration information to hosts on a TCP/IP network.
Configuration parameters and other control information are carried in tagged data items that are
stored in the options field of the DHCP message. The data items themselves are also called options.
The current set of DHCP options are documented in RFC 2131, Dynamic Host Configuration
Protocol.
Examples
The following example configures DHCP option 19, which specifies whether the client should
configure its IP layer for packet forwarding. A value of 0 means disable IP forwarding; a value of 1
means enable IP forwarding. IP forwarding is enabled in the following example:
option 19 hex 01
The following example configures DHCP option 72, which specifies the World Wide Web servers
for DHCP clients. World Wide Web servers 172.16.3.252 and 172.16.3.253 are configured in the
following example:
option 72 ip 172.16.3.252 172.16.3.253
code Specifies the DHCP option code.
instance number (Optional) Specifies a number from 0 to 255.
ascii string Specifies an NVT ASCII character string. ASCII character strings that
contain white space must be deliminated by quotation marks.
hex string Specifies dotted-hexadecimal data. Each byte in hexidecimal character
strings is two hexidecimal digits—each byte can be separated by a
period, colon, or white space.
ip address Specifies an IP address.