CIDR is killing my nerves

[David Tonhofer]

Getting to it ;-)

>> In named.conf, you would have (in my case):
>>
>> // our own reverse lookup
>>
>> zone "224.217.154.194.in-addr.arpa" {
>>         type master;
>>         file "named.rev";
>>         allow-transfer { 194.154.217.229; };
>> };

>This is it. This is what I was looking for. But how does Bind know that the
>reverse lookup zone is from 224 to 239? Why didn't you tell your bind how
>much bits your subnet has?

Your BIND doesn't need to know that. If anyone is doing a reverse lookup
on any of your IP addresses, he'll actually just be asking for a PTR
record that has as owner a domain name in the in-addr.arpa. domain. This
query will *naturally* percolate down to your nameserver. Your provider's
DNS will know to forward a query for (e.g. in my case) zone
224.217.154.194.in-addr.arpa to *your* DNS.

>> And in named.rev, you would list the PTR records
>> for the CNAMES assigned by your provider to the in-addr.arpa.
>> names corresponding to the machines on your subnetwork.
>> (which, in my case, all begin with 224.217.154.195.in-addr.arpa,
>> which as you can notice, is the base address of my CIDR
>> subnetwork), thus:
>>
>> $TTL 28800
>> $ORIGIN 217.154.194.in-addr.arpa.
>> 224             IN      SOA     dns1.synapse.lu.
>
>This here above is missing in my reverse lookup zone. But this I can also
>edit without my ISP doing anything.

...exactly!

>> dnsadmin.synapse.lu. (
>>                 2001020410 28800 7200 604800 86400 )
>>                 IN      NS      dns1.synapse.lu.
>>                 IN      NS      dns2.synapse.lu.
>> $ORIGIN 224.217.154.194.in-addr.arpa.
>> 225             IN      PTR     dns1.synapse.lu.
>> 226             IN      PTR     wk1.synapse.lu
>> 227             IN      PTR     wk2.synapse.lu.
>> etc...
>
> But this is your slave dns here.

No, this baby is the master. And it's got at authorithy for
the zone "224.217.154.194.in-addr.arpa", so it can respond
to PTR queries for

225.224.217.154.194.in-addr.arpa.
226.224.217.154.194.in-addr.arpa.
227.224.217.154.194.in-addr.arpa.

etc...which are 'specially fixed (by the provider)' zone names,
of course and not zones derived from actual IP addresses.

I hope I'm explaining this correctly. I'm self-taught here.

Best regards,

	-- David