MNAME not a listed NS record

[Jan-Piet Mens]

> Is there anything technically wrong with having a SOA MNAME field
> that isn't listed as a NS record?

Not at all; that works fine.

> The server listed as MNAME will host the zone and is authoritative
> for the zone, but out of latency concerns it isn't ideal to have
> other resolvers querying this server.

Just omit the server listed as MNAME from the NS RRset.

> Various online DNS diagnostic tools throw warnings, but as far as I
> can tell from the RFCs, this is a valid configuration. Is it valid?

Yes, it is valid. (And most of the online diagnostic tools I know suck:
for example, they complain about SOA serial numbers not being in
YYYYMMDDn format.)

> Are there any operational gotchas to be aware of or can I ignore the
> "warnings"?

You should be aware of DNS Updates which will, by default, be directed
at the server listed in SOA MNAME. If you don't do DHCP, say, then it's
fine to ignore that.

        -JP