multihomed DNS

[Barry Margolin]

In article <7u4vgm$qib$1 at nnrp1.deja.com>,  <philbird at my-deja.com> wrote:
>Hi,
>I'm having a problem figuring out how to make hosts on a multihomed
>DNS not require a fully qualified domain to refrence hosts in
>the same zone.
>
>I'm setting up a multihomed DNS server. It has 3 NICs on a subnet'd
>network (192.168.100/26).
>I'm trying to have a couple of multihomed servers respond to
>the same hostname i.e. fileserver etc.
>I've setup 3 zone files, one for each subnet,
>sub1.mydomain.com
>sub2.mydomain.com
>sub3.mydomain.com
>
>The plan was for each zone to have records such as
>
>sub1:
>192.168.100.4   IN  A  fileserver
>
>sub2:
>192.168.100.68   IN  A  fileserver
>
>sub3:
>192.168.100.130  IN A fileserver

These are backwards.  The format of an A record is:

<hostname>  IN A  <address>

>so that users would only have to NFS or telnet to 'fileserver'
>reguardless of which subnet they are on, and still go to the local
>NIC.
>
>However what I'm finding is that any domain other than the one the DNS
>server belongs to, requires a fully qualified name, which then defeats
>the idea of ussing a generic hostname that works everywhere.

The default domain is specified in the client configuration, and isn't
dependent on the DNS server.  Machines on subnet 1 should have in their
/etc/resolv.conf file:

search sub1.mydomain.com mydomain.com

Machines on subnet 2 should have:

search sub2.mydomain.com mydomain.com

and so on.  If they then do "telnet hostname" it will first look for
hostname.<theirsubnet>.mydomain.com, and if this doesn't exist it will look
for a non-subnet-specific hostname.mydomain.com.

-- 
Barry Margolin, barmar at bbnplanet.com
GTE Internetworking, Powered by BBN, Burlington, MA
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