[CentOS] mixing MX and CNAME

Tue Feb 26 05:33:17 UTC 2013
aurfalien <aurfalien at gmail.com>

On Feb 25, 2013, at 1:45 PM, Radu Anghel wrote:

> On Mon, Feb 25, 2013 at 6:06 PM, aurfalien <aurfalien at gmail.com> wrote:
>> Hi,
>> 
>> Has any one had problems with mail clients were your DNS is like this;
>> 
>> doman.com       MX      50 mail.domain.com
>> domain.com      MX      100     mail2.domain.com
>> 
>> domain.com      CNAME   www.domain.com
>> 
> 
> Hello,
> 
> You can't mix CNAMEs with other record types.
> 
> The whole domain name can't be defined as a CNAME even if you don't
> add any A/MX records to it because it *must* have NS records.
> 
> With BIND you can't even load a zone file defined like you suggested.
> named-checkzone complains:
> 
> dns_master_load: domain.com.zone:14: domain.com: CNAME and other data
> zone domain.com/IN: loading from master file domain.com.zone failed:
> CNAME and other data
> zone domain.com/IN: not loaded due to errors.
> 
> Interesting read: http://tools.ietf.org/rfc/rfc1912.txt pages 5/6 for CNAMEs.
> 
> Usually you should use something like:
> 
> domain.com    IN NS    dns.server.com.
> domain.com    IN NS    other.dns.com.
> 
> domain.com    IN A    x.x.x.x
> www.domain.com    IN CNAME    domain.com.
> 
> domain.com    IN MX    5 etc
> 
> AFAIK, SSL certs for www.domain are also valid for domain by default
> so that shouldn't be a problem.

Cool info.

I ended up mixing A, MX and NS records but not CNAMEs.

All seems to work although I am waiting for breakage, giving it another day or 2 b4 updating our external DNS.  Internal is quick to update so its easy to manage.

- aurf