Reverse lookups not working when Internet connection failed.

[Mark Andrews]

Or do what should have been done in the first place and be a unlisted secondary
of 1.66.136.193.in-addr.arpa. This way David you track the changes your ISP makes
to the zone as customers come and go. Your ISP should let you transfer this zone as it
is REQUIRED for your reverse lookups to work when you are temporally disconnected.

Any ISP that offers these delegations should be allowing their customers to transfer
the zone that contains the CNAMEs for the customer address space by default.

Mark

> On 4 Nov 2022, at 16:36, Grant Taylor via bind-users <bind-users at lists.isc.org> wrote:
> 
> On 11/4/22 10:07 AM, David Carvalho via bind-users wrote:
>> My reverse zone file
> 
> What is the origin of your zone file?  0-28.66.136.193.in-addr.arpa.?
> 
>> 1.0-28.66.136.193.in-addr.arpa.         IN      A       193.136.66.1
> 
> You seem to be using RFC 2317 Classless IN-ADDR.ARPA delegation.
> 
> As such, your reverse DNS is /dependent/ upon the parent zone; 66.136.193.in-addr.arpa., where the Classless IN-ADDR.ARPA delegation CNAME records exist.  E.g.
> 
>   1.66.136.193.in-addr.arpa.   IN   CNAME 1.0-28.66.136.193.in-addr.arpa.
> 
> It is likely this -- almost certainly -- external dependency was missing while your Internet connections was down that prevented your systems from being able to resolve reverse DNS.
> 
> Two options come to mind:
> 
> 1)  Create a bogus 66.136.193.in-addr.arpa. zone locally to host the 2317 CNAMEs.  --  This will likely have some side effects that need to be mitigated.
> 2)  Leverage Response Policy Zone(s) to try to influence the lookup as others suggested.  E.g. cause 1.66.136.193.in-addr.arpa. to become 1.0-28.66.136.193.in-addr.arpa. locally.  --  I'd have to read about how to do this.
> 
> Aside:  I see no need for 1.0-28.66.136.193.in-addr.arpa. to have an A record.  But I don't see any problem with having it either.
> 
>> 1.0-28.66.136.193.in-addr.arpa.         IN      A       193.136.66.1
>> ; Reverse mapping
>> 1       IN      PTR     dns.di.ubi.pt.
>> ...
> 
> These are the types of PTR records that I would expect to see in a reverse DNS context.
> 
> 
> 
> -- 
> Grant. . . .
> unix || die
> 
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-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742              INTERNET: marka at isc.org