[CLUE-Tech] DNS - reverse lookups for a classless subnet

[Jeremy Huber]

This is how I do it at my ISP.. not sure if this is how the RFC reads or
not:

(in the sample reverse zone file 56.34.12.in-addr.arpa)

$GENERATE 100-125 $ CNAME $.100-127
64-125   IN      NS      ns1.somedomaincustomer.com
        IN      NS      ns2.somedomaincustomer.com

This help? :)

Jeremy

----- Original Message -----
From: "Dave Anselmi" <anselmi at americanisp.net>
To: <clue-tech at clue.denver.co.us>
Sent: Wednesday, March 13, 2002 10:07 PM
Subject: Re: [CLUE-Tech] DNS - reverse lookups for a classless subnet


> Eric Batalden wrote:
>
> > i have used the DNS-HOWTO to setup up my DNS server.
> > it seems to work just fine, resolves names and address
> > both ways.  it is my understaning is that for my
> > server to "play nice" with the other servers i need to
> > account for my classless subnet.  i am looking after
> > only eight IP's.
>
> For any names you provide A records for (the names that go with your 8
> IPs) you should provide PTR records to do the reverse mapping.  Because
> there are two different zones involved, they may be delegated
> differently (i.e., your NS is authoritative for the A records but your
> ISP is authoritative for the PTR records).
>
> I don't know how ISPs usually handle this but you should ask.  At least
> you can use dig or nslookup to ask your ISP's nameservers about your IP
> addresses.  See if they tell you something generic or what you've set
> up.
>
> If you have different forward and reverse mappings, you may have
> problems using some systems (e.g., mail) that try to screen bogus
> traffic based on DNS.
>
> The best resource I think you'll find is the DNS & BIND book by Cricket
> Liu.  4th edition covering BIND 9 is out.  If you don't want to buy it,
> try various libraries--I got it through Arapahoe County once.
>
> Dave
>
>
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