Linking DNS to DHCP

Dave — Thu, 29 Jun 2006 10:59:00 +0000

If you have an office full of windows desktops but despise using the builtin DNS/DHCP services that come with network operating systems like Netware and Windows, you can still use BIND and DHCPD to handle the dynamic hostnames. This really only makes sense if you have a decent naming convention for you desktops but that’s another matter. What you want to do is give dhcpd dynamic update permissions to your internal zone. I’m going to use a simple example of a 192.168.1.0/24 subnet all in a single DNS domain called foo.com and both BIND and DHCPD running on the same server (i.e. localhost). Here is what you want your zones to look like in your named.conf file:

...
zone "foo.com"{
    type master;
    file "db.foo";
    notify yes;
    allow-update{
        localhost;
    };
};
zone "1.168.192.in-addr.arpa"{
    type master;
    file "db.192.168.1";
    allow-update{
        localhost;
    };
};
...

This gives processes running on localhost the ability to make ddns updates on those zones. Just change “localhost;” to whatever host dhcpd is bound to if it isn’t running on the same server. You can also specify multiple hosts or a whole subnet using the “192.168.1.0/24″ format. After you have configured BIND it’s time to tell dhcpd where to send updates. You do this by adding the following to your dhcpd.conf file:

ddns-update-style   interim;
...
subnet 192.168.1.0 netmask 255.255.255.0 {
  ...
  ddns-updates on;
  ddns-domainname "foo.com.";
  ddns-rev-domainname "in-addr.arpa.";
  ...
}
...
zone foo.com. {
    primary localhost;
}
zone 1.168.192.in-addr.arpa. {
    primary localhost;
}
...

This tells dhcpd where to send ddns update requests and for what domains. Be sure to monitor your syslog as you fire everything up to make sure you aren’t getting any ddns errors from either of the two daemons.

Southern Bread » dhcp

Linking DNS to DHCP