MX preference

[D. Stussy]

On 7 Sep 1999 jdenz at my-deja.com wrote:
> Is a preference value required if there is only
> one mail server for a zone?
> 
> ie; can it be:
> 
> mx   mail.mydomain.com
> 
> or must it be:
> 
> mx 10 mail.mydomain.com
> 
> thanks,
> 
> jonathan

The number must be present, but if there's only ONE MX RR for a host, the value
of the number is irrelevent.  The number is used only for comparison among
various MX records.