User guide

86 Chapter 4. Configuring Special Features
Concepts
The server returns values for options explicitly requested in the client request. It selects the values to return
based on the following algorithm:
1. If the value is defined for the client, then the server returns the requested value for an option.
2. If the value for the option has not been set for the client, then the server returns the value option if it has
been defined for the subnetwork.
3. If the value option does not exist for the client and does not exist for the subnetwork, then the server
returns the value option if it has been defined globally.
4. If the value option is not defined anywhere, the server does not return any value for that option in its
reply to the client request.
Important: When the server replies to a client:
¥ It does not return any option values not requested by the client.
¥ It does not support the definition of a ÒclassÓ of clients.
¥ It does not return any non-default option values unless the client requests the option value and the server
has a value defined for that option.
¥ It does not return any non-default values on the clients subnet unless the client requests the value for that
option.
Commands for Global Option Values
To set the value for a global option, use:
dhcp set valueoption <code> <value>...
The code can be a number between 1 and 61 or a keyword.
To see the list of predefined and user-defined options, use:
dhcp list definedoptions
To clear the value for a global option, use:
dhcp clear valueoption <code>
Example:
To set the global value for the domain name server option, enter:
dhcp set valueoption domainnameserver 192.168.254.2 192.168.254.3
Commands for Specific Option Values for a Subnetwork
To set the value for an option associated with a subnetwork, use:
dhcp set valueoption <net> <code> <value>...
To clear the value for an option associated with a subnetwork, use:
dhcp clear valueoption <net> <code>
Examples:
dhcp set valueoption 192.168.254.0 gateway 192.168.254.254
dhcp set valueoption 6 192.84.210.75 192.84.210.68