From kragen@dnaco.net Tue Aug 25 08:54:38 1998 Date: Tue, 25 Aug 1998 08:54:36 -0400 (EDT) From: Kragen To: systalk@ml.org Subject: Re: [ST] I need help with reverse DNS lookups In-Reply-To: <35E2AB6B.D8227AB9@telrad.co.il> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Keywords: X-UID: 1396 Status: O X-Status: On Tue, 25 Aug 1998, Meir wrote: > Kragen wrote: > > :) Actually, RFC 2371 is the "Transaction Internet Protocol", and > > doesn't say anything about CNAMEs or in-addr.arpa. > > And unfortunately couldn't help to *_set up_* ISP's environment :) > but anywhere, thanks to George for his care and to Kragen for > his RFC knowledge :) To set up, you need three things: 1 a nameserver; 2 delegation of the appropriate in-addr.arpa domain to your nameserver; 3 data on your nameserver to answer appropriate queries. The name 4.3.2.1.in-addr.arpa. is where one goes to do a reverse DNS lookup for the IP address 1.2.3.4. One looks there for a PTR record; the value of the PTR record is the hostname. So #2 means that, in order to serve up that record, you need one of the following: a. the nameserver that controls in-addr.arpa. to delegate 1.in-addr.arpa. to your nameserver; b. the nameserver that controls 1.in-addr.arpa. to delegate 2.1.in-addr.arpa. to your nameserver; c. the nameserver that controls 2.1.in-addr.arpa. to delegate 3.2.1.in-addr.arpa. to your nameserver; d. the nameserver that controls 3.2.1.in-addr.arpa. to delegate 4.3.2.1.in-addr.arpa. to your nameserver. This is accomplished with a record like this (for example (c)): 3.2.1.in-addr.arpa. IN NS your.nameserver.telrad.co.il. (Preferably you will have multiple nameservers.) #3 means that your nameserver will have a record like this: 4.3.2.1.in-addr.arpa. IN PTR some.host.telrad.co.il. (Of course, these records will probably be abbreviated a bit, but they'll work as is. Just change the numbers and the hostnames.) The BIND Operations Guide, or BOG, explains all this. Kragen -- Kragen Sitaker We are forming cells within a global brain and we are excited that we might start to think collectively. What becomes of us still hangs crucially on how we think individually. -- Tim Berners-Lee, inventor of the Web