[Remops] why does dingo have two mx hosts with the same IP?

[Anonymous]

On Thu, 16 Feb 2006 20:40:03 +0100 (CET), you wrote:
>
> $ dig mx dingoremailer.com
> ...
> ;; ANSWER SECTION:
> dingoremailer.com.      6559    IN      MX      0 smtp.dingoremailer.com.
> dingoremailer.com.      6559    IN      MX      0 mail.dingoremailer.com.
>
> ;; ADDITIONAL SECTION:
> mail.dingoremailer.com. 6559    IN      A       208.180.124.28
> smtp.dingoremailer.com. 6559    IN      A       208.180.124.28
>
> ?!?

There are advantages to having your first preference MX host as 
an additional least preference MX host. This is because you are 
often in full control of this machine and can easily customise 
anti-spam features to reject mail at SMTP delivery time. Some 
viruses and spammers intentionally send mail to the least 
preference MX host, as they know that secondary MX machines are 
often not as closely controlled.

This would only make any sense if dingo has a third MX record, 
of course. Perhaps it is only used temporarily and is currently 
absent from the DNS? It would also need the preferences to be 
different (in Dingo's case, they are both set the same).