NXRRSET
Chris Buxton
cbuxton at menandmice.com
Wed May 6 17:17:31 UTC 2009
On May 6, 2009, at 7:49 AM, Thilanka Samarasekera wrote:
> Hello,
>
> I am running BIND version 9.2.3 on a Solaris 9 box. Every now and
> then I will see the following in my DNS cache:
>
> domain.com. 458 \-AAAA ;-$NXRRSET
>
> If I force a MX record lookup it does get the correct MX records for
> "domain.com". The explanation I have for "NXRRSET" is "Its the
> number od queries the name server handled that resulted in responses
> saying that the type of record the querier requested didn't exist
> for the domain name it specified". If do a MX record look for
> "domain.com" it does get the correct entries and caches it for the
> specified TTL. My question is how do I go about identifying what's
> causing my BIND server to cache a query with the flag "NXRRSET" ?
The query getting the negative response here is for an AAAA record
named domain.com. For example, there might be:
example.com. MX 10 mx.example.com.
mx.example.com. A 192.0.2.1
Your cache might then end up with an NXRRSET (no such resource record
set) for mx.example.com/IN/AAAA, because the mail server is looking
for IPv6 addresses for the mail server.
Chris Buxton
Professional Services
Men & Mice
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