one A record, different IP address

[Mathias Körber]

> I have a rather general question.  Is it possible to have one host (A)
> record point to multiple IPs?

It is possible, but that's not one A record, it's two A records inthe
same RRset (Resource Record Set =3D all records which share a common =
owner
[left-hand-side+$ORIGIN], class and type). Note that all records in an
RRset should (must? I think Bind-9 enforces this, but I'll have to
check that again) have the same TTL.

> For example
>=20
> WWW    IN    A   204.94.91.4
> WWW    IN    A   204.94.91.3

This is fine. Resolvers should see both addresses, in a (pseudo-)random
order. Applications should contact the first address returned by the
resolver, and if that fails fall back to the other one. This gives
rudimentary load-balancing.

Applications should stick to the one address that works for the duration
of a networking session (and use the same address for additional
connections if required), and only query/select another address if the =
session
is terminated or closed.

regards