If you provide your local network with your own DNS services, you might want to use more than a single DNS server.
If you use two or more DNS serers, you might want to set them up as a master / slave combination, which allows you to maintain your DNS configuration on a single machine, while the others copy the DNS entries from the master to the slave machines regulary and automatically.
On Mac OS X Server, many people expect reverse lookup replication to work differently from how it does.
Yet, it works fine on Mac OS X Server 10.4.9, and here is how it goes:
1. Set up your DNS master and activate zone transfers.
2. Go to your secondary DNS server, and look at DNS->Settings->Secondary Zones.
A slave configuration with lookups (name resolves to IP address) and reverse lookups (IP address resolves to name) working should look something like this:
The domain used here is aulichadamski.homeunix.org, with the local subnet of 10.0.2.0/24.
To add this configuration, click the “+” button and first enter
where aulichadamski.homeunix.org is the local domain name, and 10.0.2.206 is the IP address of the primary DNS server.
Now do the same for the reverse lookups:
As you see, 10.0.2.0 transforms into 2.0.10. Do this for your subnet accordingly.
As soon as you click on SAVE and start the service, your secondary DNS server will copy the accompanying DNS files from the primary server to the local file path /var/named/.
If you list this directory, you should now see something like
odmaster:/var/named root# ls -al
total 40
drwxr-xr-x 7 root wheel 238 May 25 14:55 .
drwxr-xr-x 32 root wheel 1088 May 25 14:59 ..
-rw-r--r-- 1 root wheel 572 May 23 11:54 2.0.10.in-addr.arpa.bak
-rw-r--r-- 1 root wheel 585 May 25 14:55 aulichadamski.homeunix.org.bak
-rw-r--r-- 1 root wheel 195 Jul 2 2006 localhost.zone
-rw-r--r-- 1 root wheel 2498 Jul 2 2006 named.ca
-rw-r--r-- 1 root wheel 296 May 23 11:54 named.local
odmaster:/var/named root#
where the files with the suffix “.bak” hold a copy of the primary DNS server’s DNS entries.
That’s it!