Reverse lookups not working when Internet connection failed.

[Lyle Giese]

The queries should work if you query an authoritative dns server for 
that zone.  If you are querying a recursive only server(when Internet 
connection is down), it won't be able to find the authoritative server 
and will answer only if it has valid cached answer. Once that cached 
answer expires or is not there, a recursive only server will fail to 
give you the answer you seek.

That is very dependent on your internal dns setup and the type of dns 
server you are querying.

Lyle Giese

On 11/4/22 11:07, David Carvalho via bind-users wrote:
> Thanks for the replies.
> My reverse zone file
>
> $TTL 86400
> @       IN      SOA     di.ubi.pt. postmaster.di.ubi.pt (
>                          2020040401      ; serial
>                          28800           ; refresh 3h
>                          7200            ; retry 1h
>                          604800          ; expire 1w
>                          86400 )         ; ttl 1d
>
> ; Servidores de nomes
>
>          IN      NS      dns.di.ubi.pt.
>          IN      NS      dns2.di.ubi.pt.
>
> 0.0-28.66.136.193.in-addr.arpa.         IN      A       193.136.66.0
> 1.0-28.66.136.193.in-addr.arpa.         IN      A       193.136.66.1
> 2.0-28.66.136.193.in-addr.arpa.         IN      A       193.136.66.2
> 3.0-28.66.136.193.in-addr.arpa.         IN      A       193.136.66.3
> 4.0-28.66.136.193.in-addr.arpa.         IN      A       193.136.66.4
> 5.0-28.66.136.193.in-addr.arpa.         IN      A       193.136.66.5
> 6.0-28.66.136.193.in-addr.arpa.         IN      A       193.136.66.6
> 7.0-28.66.136.193.in-addr.arpa.         IN      A       193.136.66.7
> 8.0-28.66.136.193.in-addr.arpa.         IN      A       193.136.66.8
> 9.0-28.66.136.193.in-addr.arpa.         IN      A       193.136.66.9
> 10.0-28.66.136.193.in-addr.arpa.        IN      A       193.136.66.10
> 11.0-28.66.136.193.in-addr.arpa.        IN      A       193.136.66.11
> 12.0-28.66.136.193.in-addr.arpa.        IN      A       193.136.66.12
> 13.0-28.66.136.193.in-addr.arpa.        IN      A       193.136.66.13
> 14.0-28.66.136.193.in-addr.arpa.        IN      A       193.136.66.14
>
> ; Reverse mapping
>
> 1       IN      PTR     dns.di.ubi.pt.
> 2       IN      PTR     dns2.di.ubi.pt.
> 3       IN      PTR     geodac.di.ubi.pt.
> ...
>
>
>
>
> -----Original Message-----
> From: bind-users <bind-users-bounces at lists.isc.org> On Behalf Of Matus UHLAR
> - fantomas
> Sent: 04 November 2022 16:02
> To: bind-users at lists.isc.org
> Subject: Re: Reverse lookups not working when Internet connection failed.
>
> On 04.11.22 15:41, David Carvalho via bind-users wrote:
>> We've had an internet failure for a few days last week and as services
>> got online I found the following:
>>
>> Dns queries about my.domain from my.domain  worked as expected. Since
>> there was no internet connection, I obviously couldn't  query the outside
> world.
>> Reverse (PTR) Dns queries about my.domain from my.domain didn't work.
>> Now that the internet connection is restored, everything is ok.
>>
>>
>>
>> The reverse entries are in the format  "z.y.x.in-addr.arpa."    for IP
> x.y.z
>> Aren't they supposed to work locally when no outside connection is
>> available?
> if they are properly configured, yes.
>
>> What could I be missing?
> can you provide an example of an IP and configured reverse zone, and the
> zone file?
>
> --
> Matus UHLAR - fantomas, uhlar at fantomas.sk ; http://www.fantomas.sk/
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