On Thu, May 03, 2001 at 12:53:44PM -0400, Kris von Mach wrote:
> At 08:34 AM 5/3/2001 -0600, you wrote:
> > Unfortunately I do not control my PTR records so I have to do the dns name
> > change with CNAME.
> >
> > My questions are:
> >
> > Can MX record point to a CNAME?
>
CC --> No, never.
>
> Charles,
>
> Why can't it be a CNAME? Is there a reason for this? I am currently using it
> as a CNAME and it's been working fine for a year or so... If there is a good
> reason for it, I sure would like to know so I can make changes.
It's not actually a _violation_, as such, but RFC1034 (one of the DNS
specification RFCs) says that:
"If a CNAME RR is present at a node, no other data should be
present; this ensures that the data for a canonical name and its aliases
cannot be different. This rule also insures that a cached CNAME can be
used without checking with an authoritative server for other RR types."
This means that pointing MX, NS, and SOA (at least) at a CNAME is not
recommended. Personally, I hate CNAME, and I almost never use it. I can
think of only one specialized use where CNAME comes in handy
(third-party hosting). Nearly everything else can be done more
efficiently with multiple A records IMHO.
P.S. If someone has a reference to an RFC which says 'must not' rather
than 'should not', I'll be happy to use it from now on. :)
