[57325] in North American Network Operators' Group
An A record is an MX record and is a missing MX....
daemon@ATHENA.MIT.EDU (Gerardo Gregory)
Thu Apr 3 17:04:31 2003
In-Reply-To: <3E8CA8CE.72E4612@onecall.net>
From: "Gerardo Gregory" <ggregory@affinitas.net>
To: Richard Irving <rirving@onecall.net>
Cc: nanog@merit.edu
Date: Thu, 03 Apr 2003 15:58:53 -0600
Errors-To: owner-nanog-outgoing@merit.edu
Please forgive if this has been discussed, beaten, or decided previously
here on the list. A recent issue I encountered has prompted me to ask the
following question. What I am looking for is clarification regarding the
"proper" way of implementing Mail Exchange records, etc.
I have always been under the impression (or taught at least) that an MX
record was necessary (required) for mail exchange. I at least believed that
this was the correct way. Recently, we implemented a new mail server at our
facility and started having some issues relaying mail to a few domains.
Although this has already been resolved, I was under the impression that
these two domains where the actual problem since I could not resolve an MX
record for either one.
Since then I have learned that some MTA's will look for an A record if it
cannot find an MX record and use the A record instead.
Is this acceptable (in a "best case scenario") as a correct method?
Obviously some admins I have encountered are starting to host mailservers
for sub-domains and domains without MX entries on their DNS zone records.
Relying on the A record alone.
Gerardo A. Gregory
