Multiple A records

[Barry Margolin]

In article <9ve4oa$nc0 at pub3.rc.vix.com>,
McNutt, Justin M. <McNuttJ at missouri.edu> wrote:
>
>Is there anything wrong with having multiple A records for the same IP
>address?  E.g.:
>
>this.missouri.edu.  IN  A  10.1.1.1
>that.missouri.edu.  IN  A  10.1.1.1
>
>...etc.
>
>Of course, 10.1.1.1 will only have one PTR record.
>
>Anyway, this just looks wrong to me, but I can't explain it to the people
>who want the names.  IS there anything wrong with it (aside from making it
>harder to hunt down all of the names when 10.1.1.1 gets retired)?

As Joe said, it's fine as far as the DNS protocol is concerned.  However,
to avoid the problem of hunting down all the names I recommend using CNAME
records whenever possible:

this.missouri.edu. IN A 10.1.1.1
that.missouri.edu. IN CNAME this.missouri.edu.

You can't do this is that.missouri.edu is the target of an MX or NS record,
or has any other records of its own.  This latter rule means you can't make
the zone name itself be a CNAME record, so you can't do:

missouri.edu.     IN CNAME www.missouri.edu.
www.missouri.edu. IN A     1.2.3.4

On the other hand, you *can* do:

missouri.edu.     IN A     1.2.3.4
www.missouri.edu. IN CNAME missouri.edu.

-- 
Barry Margolin, barmar at genuity.net
Genuity, Woburn, MA
*** DON'T SEND TECHNICAL QUESTIONS DIRECTLY TO ME, post them to newsgroups.
Please DON'T copy followups to me -- I'll assume it wasn't posted to the group.