Where does this CNAME record belong?

Answered Thu, 9 May 2002

> The do's and don'ts of CNAMES
>
> I am perplexed and stupefied over cnames.
>
> I have tried to gather info from many sources but as I find some info,
> another door opens behind it and I find myself scratching my head.
>
> Here is the scenario:
> I have NS's running Bind 9.1
> I have a request to create cnames for zones that have to follow a
> new naming
> standard.
> So the new zone is for example newzone.mybox.com.
> The customer has a web site that is well known and wants to retain the old
> name, however, the old name is www.oldzone.mybox.com.
>
> So I have tried to create a cname in a zone file for newzone.mybox.com
>
> www.oldzone.mybox.com. IN CNAME server.newzone.mybox.com.
>
> Of coarse I get a syslog error stating that the oldzone.mybox.com is
> out-of-zone data. I have read that bind 9.x has this error where
> as earlier versions may not have.

Actually, that message has been around since about BIND 4.9.

> Every example of CNAME's I have seen always have the
> alias within the same zone.
>
> www.newzone.mybox.com. IN CNAME server.newzone.mybox.com.
>
> I have come across a few examples where people were trying to
> accomplish the same thing. But it seemed to be earlier Bind versions.
>
> the solution that I have come up with is to create a completely new zone
> file for oldzone.mybox.com and use an A record to point the service to the
> servers IP address.
>
> But I don't know if this is the best way or if I should do or could do
> something else.

Well, I don't know what the disposition of the oldzone.mybox.com zone
is. Does the customer run his own name servers for the one? Can you
add a CNAME record to its zone data file, like this:

www.oldzone.mybox.com. IN CNAME server.newzone.mybox.com.

That's where the record belongs. You determine that by looking at the
domain name on the left side (the "owner name"). That domain name is
in the oldzone.mybox.com zone, so that's the zone data file you put it
in.

> I had thought about using a DNAME but this does not seem to fit the bill.
> Since the customer wants to retain the old name for his customers, and not
> replace it with the new zone and visa versa.

Right.

> If you could help me with the proper use of CNAMEs and any suggestions on
> what direction I should go.

I hope this helps you.

cricket