DNS MX records for subdomains

[Mathias Körber]

> I have a DNS setup & working correctly (AFAIK).
>=20
> I want to create separate mail domains for departments for this =20
> mail to be=20
> handled separately as follows:
>=20
> My.domain	MX	10	mail.my.domain
> 		MX	20	other.my.domain
>=20
> I would have expected that mail to user at sub.my.domain would =
automatically=20
> get handled without the need for a wildcard DNS record.  However, the =
DNS=20
> server would respond with a "domain unknown" type of error.
>=20
> I ended up doing
> My.domain	MX	10	mail.my.domain.
> 		MX	20	other.my.domain.
> sub1		MX	10	mail.sub1.my.domain.
> 		MX	20	mail.my.domain.
> 		MX	30	other.my.domain.
> sub2		MX	10	mail.sub2.my.domain.
> 		MX	20	mail.my.domain.
> 		MX	30	other.my.domain.
>=20
> This correctly gets the mail to the sub-domain mail server.  Is this =
the=20
> expected BIND behavior and were *my* expectations incorrect?

This is the expected behaviour. Your first set of MX records only =
specifies
that all mail to user at My.comain. is to be routed there.

You could have made do with a wildcard MX record in the parent zone:


$ORIGIN My.domain.
*		MX	10	mail.my.domain
 		MX	20	other.my.domain

which will apply to all user@<anything>.my.domain, unless a more =
specific
MX record for a certain host/subdomain exists.

regards