Mark Andrews wrote:

>>Hi all
>>
>>I have been scratching my head for the past two - three days to come
>>to terms with an inexplicable (atleast it seems so to to me )
>>behaviour of dig. Let me explain it ..
>>
>>We have an internal domain in the private ip space , which cannot be
>>looked up from external world. When I do a dig -x from our
>>internal name server
>>
>> say dig -x 10.1.1.1
>>
>>gives the host name right
>>
>>but the authority section is from the root zone
>>-----------
>>;; AUTHORITY SECTION:
>>10.in-addr.arpa. 9h6m59s IN NS BLACKHOLE-1.IANA.ORG.
>>10.in-addr.arpa. 9h6m59s IN NS BLACKHOLE-2.IANA.ORG
>>
>>------------
>>
>>When I follow that up with a qury like
>>
>> dig ns 1.1.10.in-addr.arpa
>>
>>I get the name servers right ( that of our internal domain )
>>
>>and now when I try to reverse lookup any ip in the internal domain
>>the authority section of the answer is coming out absolutely right
>>ever after .
>>
>>thoughts/comments ?
>>Sai.
>>
>>
>>

>
> You made a reverse lookup for a 10.x.x.x address not in
> 10.1.1.x ~6.5 days ago and the cache has the NS records
> for 10.in-addr.arpa as a result.
>
> The NS records for 1.1.10.in-addr.arpa have timed out and
> you still have the PTR record for 1.1.1.10.in-addr.arpa.
>
> If this bothers you use a slave / stub zone for
> 1.1.10.in-addr.arpa.
>

Or, even better, set up 10.in-addr.arpa on your servers so that reverse
lookups for _mistyped_ 10.*.*.* addresses are contained within your
network instead of bugging the poor iana.org nameservers...


- Kevin