MNAME not a listed NS record

[Chuck Swiger]

On Jan 16, 2013, at 12:40 PM, Dave Warren wrote:
> Is there anything technically wrong with having a SOA MNAME field that isn't listed as a NS record?

Sure.  The SOA MNAME is expected to be the "primary master" nameserver for the zone; it's where things like dhcpd and such send dynamic updates for the zone to.

> 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.

Okay...so why would you use that nameserver at all, then?

Choose a nameserver which is suitable for other resolvers to query for your master.

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

It's not valid, but if you aren't doing dynamic updates to the zone, and you can live without SOA serial # sanity checking by slave nameservers trying to determine whether the zone has been updated or not by checking with the MNAME server, sure, you can setup DNS in such a fashion and (probably) nothing else would break.

Regards,
-- 
-Chuck