CNAME RRs

[Barry Margolin]

In article <9od8av$5c at pub3.rc.vix.com>,
Richard Willmann <mailinglists at nocomment.sk> wrote:
>
>hello,
>
> i would like to ask according to DNS glossary founded on Men&Mice web site
>about CNAME RRs. The CNAME RR according to RFC1035 can not share owner name
>with any other RR. But, this time I have found following statement:
>
>--- CUT ---
>A domain name that has a CNAME record can't have any children. So if
>glossary.example.com has a CNAME record, Then jobs.glossary.example.com is
>improper.
>--- CUT ---
>
> ??? it is true? If yes, according to what?

I know of no such rule, and we violate that rule extensively in one of our
domains and have never had a problem.  All our routers have entries in the
bbnplanet.net domain like:

loopback0.<routername> IN A 1.2.3.4
serial0.<routername>   IN A 4.3.2.1
<routername>           IN CNAME loopback0.<routername>

> on the other hand, is multiple CNAME RR with same owner (alias) name
>"officialy" permited (for may be load balancing issues). I know, that the
>newer version of bind name server have a special switch to allow this, but i
>can not found any RFC and/or other document on the net, where this is
>clarificated.

No, multiple CNAMEs is not permitted.  The switch is only there to enable
backward compatibility with old versions of BIND that didn't reject such
entries.  If you want load balancing, use multiple A records, not multiple
CNAME records.

-- 
Barry Margolin, barmar at genuity.net
Genuity, Woburn, MA
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