System Administration Guide: IP Services

The dhcptab Table

The dhcptab table contains all the information that clients can obtain from the DHCP server. The DHCP server scans the dhcptab each time it starts. The file name of the dhcptab varies according to the data store used. For example, the dhcptab created by the NIS+ data store SUNWnisplus is SUNWnisplus1_dhcptab.

The DHCP protocol defines a number of standard items of information that can be passed to clients. These items are referred to as parameters, symbols, or options. Options are defined in the DHCP protocol by numeric codes and text labels, but without values. Some commonly used standard options are shown in the following table.

Table 7–1 Sample DHCP Standard Options





Subnet mask IP address 


IP address for router 


IP address for DNS server 



Text string for client host name 



DNS domain name 

Some options are automatically assigned values when the administrator provides information during server configuration. The administrator can also explicitly assign values to other options at a later time. Options and their values are passed to the client to provide configuration information. For example, the option/value pair, DNSdmain=Georgia.Peach.COM, sets the client's DNS domain name to Georgia.Peach.COM.

Options can be grouped with other options in containers known as macros, which makes it easier to pass information to a client. Some macros are created automatically during server configuration, and contain options that were assigned values during configuration. Macros can also contain other macros.

The format of the dhcptab table is described in dhcptab(4) man page. In DHCP Manager, all the information shown in the Options and Macros tabs comes from the dhcptab table. See About Options for more information about options, and About Macros for more information about macros.

Note that the dhcptab table should not be edited manually. You should use either the dhtadm command or DHCP Manager to create, delete, or modify options and macros.