What do I put in the MNAME field of the SOA record for 0.0.127.in-addr.arpa?

Answered Tue, 23 Apr 2002

> I am rather new to DNS and will have to forgive me for asking a silly question.

That's perfectly okay.

> It is my understanding the SOA MNAME field is used to point to the master
> server for a particular zone. my question is how is the SOA used in the
> loopback file 0.0.127.in-addr.arpa? Does it point to the local
> machine name as the master for itself. It seems that it should based on the
> definition of the SOA MNAME field. For example I have a zone, that I have
> created for all machines, that I manage throughout the environment. let's call it
> zone managed of mybox.com. I have a master server where all zones are
> created and 2 slave servers. server names are ns1, ns2, ns3. So for the
> master server, I have the SOA of the 0.0.127.in-addr.arpa db file as
> ns1.managed.mybox.com. Now should I have this in my loopback file for my
> slave servers or should I have an SOA of ns2. managed.mybox.com. and
> ns3.managed.mybox.com. respectively. I currently have the loopback pointing
> to each host. I have tried it with ns1 and ns2 as the SOA for 0.0.127.in-addr.arpa
> and they both seem to work.

Well, the MNAME field is only used to determine where to send dynamic
updates and where *not* to send NOTIFY messages. So unless you're
dynamically updating your 0.0.127.in-addr.arpa zone (which I doubt)
or are running slave name servers for the zone (which is possible),
you don't need to worry about it. If you have slave name servers for
the zone, use the primary master's domain name in the MNAME field so
they all know not to notify the primary master.

> What is the significance of the loopback file and should it be
> configure for each host differently or the same as the master server?
> or does it not matter at all?

It just reverse maps the IP address 127.0.0.1 to "localhost."

> this is a silly little file.

Sure is.

> love the book by the way. it has helped as I am under pressure to
> learn dns in a short period of time.

I'm glad!

cricket