From owner-freebsd-questions Sun Jul 30 4:17:38 2000 Delivered-To: freebsd-questions@freebsd.org Received: from web3202.mail.yahoo.com (web3202.mail.yahoo.com [204.71.202.199]) by hub.freebsd.org (Postfix) with SMTP id 7F1EC37B511 for ; Sun, 30 Jul 2000 04:17:31 -0700 (PDT) (envelope-from danfairs@yahoo.co.uk) Message-ID: <20000730111726.13738.qmail@web3202.mail.yahoo.com> Received: from [212.49.246.182] by web3202.mail.yahoo.com; Sun, 30 Jul 2000 12:17:26 BST Date: Sun, 30 Jul 2000 12:17:26 +0100 (BST) From: =?iso-8859-1?q?Dan=20Fairs?= Subject: Re: reverse dns To: Roelof Osinga , Evren Yurtesen Cc: freebsd-questions@FreeBSD.ORG MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > But they also are in a position to steer you in the direction of > the one they provided the blocks to. Most likely their NS will > either hold the reverse data or in turn knows where to steer > you next. > > Roelof Hi, There is a system for doing this. In a nutshell, when you put an address into the DNS system, you enter a mapping that looks like this: foo.bar.com. IN A 123.456.789.123 This will allow you to look up the IP for foo.bah.com. When this mapping is entered into the DNS, it is common to also enter another mapping: 123.789.456.123.in-addr.arpa. IN PTR foo.bar.com. This permits reverse lookups, as the resolver doing the reverse lookup simply reverses the address it wants to look up, bungs the in-addr.arpa. domain on the end, and queries the nameserver for the appropriate PTR record. This would return, in this case, foo.bar.com. I've skimmed over a lot of the detail here - I'd recommend the O'Reilly book, 'DNS and BIND', by Paul Albitz and Cricket Liu, which will tell you everything you could ever want to know about DNS. Hope this helps, Dan ===== Daniel Fairs dan@spiderplant.no-spam.net System Administrator spiderplant.net ____________________________________________________________ Do You Yahoo!? Get your free @yahoo.co.uk address at http://mail.yahoo.co.uk or your free @yahoo.ie address at http://mail.yahoo.ie To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message