MX record IP address instead of hostnames

[Eivind Olsen]

Karen Lear wrote:

> Can anyone tell me why my MX record for the coop-uspto.gov domain are IP
> addresses instead of hostnames?
...
> Non-authoritative answer:
> coop-uspto.gov  mail exchanger = 5 151.207.128.23.coop-uspto.gov.
> coop-uspto.gov  mail exchanger = 5 151.207.128.22.coop-uspto.gov.

I can't, no. It looks fine enough when I check here (a bit odd to only
have a single nameserver, but that's beside the point).

[eivind at vimes ~]$ dig +short mx coop-uspto.gov
5 coop-mbxhc-1.coop-uspto.gov.
5 coop-mbxhc-0.coop-uspto.gov.
[eivind at vimes ~]$

Regards
Eivind Olsen