PTR records

[Michele Chubirka]

I thought it was very BAD form to have two A records pointing to the same
IP. You're not supposed to do this, it's a conflict, right?

-----Original Message-----
From: stu at vixie.stac.state.tx.us [mailto:stu at vixie.stac.state.tx.us]On
Behalf Of stuart nichols
Sent: Wednesday, September 27, 2000 6:38 PM
To: Michele Chubirka
Cc: comp-protocols-dns-bind at moderators.isc.org
Subject: Re: PTR records




On Wed, 27 Sep 2000, Michele Chubirka wrote:

> This is probably going to sound like a stupid question, but if I
> have an A record and a CNAME record, how many pointer records
> should I have. One, right? Which uses the A name, not the CNAME
> record, is this correct?

In the case of an A record and a CNAME record, then by definition
you should only have one pointer record.  For example:

  bob		in	a	10.0.0.210
  fred		in	cname	bob

The CNAME record for fred means "substitute bob whereever you see
fred", because the real name (the CANNONICAL name) for "fred" is
"bob".

If you want the name fred to stand on its own, then you give
them both identical AA records:

  bob		in	a	10.0.0.210
  fred		in	a	10.0.0.210

Then you could give two pointer records, one pointing to the name
"fred", the other pointing to the name "bob", but as Joe Yao pointed
out, software doesn't make use of multiple pointer records.

--

stu
office: (512) 463-7601
FAX:    (512) 475-4759

stuart nichols
State Technology Assessment Center
Texas Department of Information Resources
300 West 15th Street
Suite 1300
Austin  TX  78701