Re: [ipv6-wg@localhost] Reverse lookup

[Alexander Gall <]

On Tue, 8 Apr 2003 16:31:32 +0200, Matthias Cramer cramer@localhost said:

> On Tue, 8 Apr 2003 16:25:57 +0200
> "BEGIN, Thomas" tbegin@localhost wrote:

>> Hello everyone,
>> 
>> I'm testing DNS over IPv6 on a testbed and I'm confronted to an issue.
>> 
>> Here is my configuration: I'm working on a Red Hat Distribution (8.0) with Bind 9.2.1.9
>> 
>> I've set up configuration files and the forward lookup works over IPv4 and IPv6 but the reverse lookup is only working with IPv4.
>> 
>> (fec0:0:0:1::2 is one of the site-local addresses of my machine (DNS server))
>> e.g. host fec0:0:0:1::2 gives me: 
>> Host \[xFEC00000000000010000000000000002].ip6.arpa not found: 2(serverfail)
>> 
>> First I realized that even if I tried to use ip6.int suffix in the configuration files, the message error keeps the same - Host \[xFEC00000000000010000000000000002].ip6.arpa not found: 2(serverfail) !!!
>> 
>> Secondly, by sniffing with ethereal the packets, I've seen that the query is well sent to the computer (loop back) but no response is given and then computer tries to ask root DNS...
>> 
>> I'm not out of idea, may be one of you can help me ...


> The problem is, that the host command asks for an A6 record and your
> DNS uses AAAA records (which is correct).

No, host *does* make an inverse (i.e. PTR) query, but it uses the
old-style bit-label/ip6.arpa (RFC2874) combination by default.
Bit-lables were never widely used and the RFC has been moved to
experimental status by RFC3363.

You can change that behavior to nibble-label/ip6.int (RFC1886) with
the -n option of the host command.  Actually, that is deprecated as
well by RFC3152.  The Right Thing nowadays is nibble-lables in
ip6.arpa.  If you want to be sure that inverse queries always work,
you should have ip6.arpa as well as ip6.int and set them up
identically for the time being.  Oh, well.

-- 
Alex