Solaris DHCP Administration Guide

Updating System Files and Netmask Tables

During the configuration process, DHCP Manager or the dhcpconfig utility scans various system files on your server for information it can use to configure the server.

You must be sure the information in the system files is current before you run DHCP Manager or dhcpconfig to configure your server. If you notice errors after you configure the server, use DHCP Manager or dhtadm to modify the macros on the server.

The following table lists some of the information gathered during DHCP server configuration, and the sources for the information. Be sure this information is set correctly on the server before you configure DHCP on it. If you make changes to the system files after you configure the server, you should reconfigure the service to pick up the changes.

Table 2–2 Information for DHCP Configuration




Time zone 

System date, time zone settings 

The date and time zone are initially set during the Solaris installation. You can change the date by using the date command and change the time zone by editing the /etc/TIMEZONE file, which sets the TZ variable.

DNS parameters 


The DHCP server uses the /etc/resolv.conf file to look up DNS parameters such as DNS domain name and DNS server addresses. See “Setting Up DNS Clients” in Solaris Naming Setup and Configuration Guide for more information about resolv.conf.

NIS or NIS+ parameters 

System domain name, nsswitch.conf, NIS, NIS+

The DHCP server uses the domainname command to obtain the domain name of the server system, and the nsswitch.conf file to determine where to look for domain-based information. If the server system is a NIS or NIS+ client, the DHCP server queries NIS or NIS+ services to get NIS/NIS+ server IP addresses.

Default router 

System routing tables, user prompt 

The DHCP server searches the network routing tables to find the default router for clients attached to the local network. For clients not on the same network, the DHCP server must prompt the administrator for the information. 

Subnet mask 

Network interface, netmasks table

The DHCP server looks to its own network interfaces to determine the netmask and broadcast address for local clients. If the request had been forwarded by a relay agent, the server looks up the subnet mask in the netmasks table on the relay agent's network.

Broadcast address 

Network interface, netmasks table

For the local network, the DHCP server obtains the broadcast address by querying the network interface. For remote networks, the server uses the BOOTP relay agent's IP address and the remote network's netmask to calculate the broadcast address for the network.