From owner-freebsd-questions@FreeBSD.ORG Thu Mar 27 10:44:08 2003 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 2B95537B401 for ; Thu, 27 Mar 2003 10:44:08 -0800 (PST) Received: from malkav.snowmoon.com (malkav.snowmoon.com [209.23.60.62]) by mx1.FreeBSD.org (Postfix) with SMTP id C657143FAF for ; Thu, 27 Mar 2003 10:44:06 -0800 (PST) (envelope-from jaime@snowmoon.com) Received: (qmail 60735 invoked from network); 27 Mar 2003 18:44:05 -0000 Received: from localhost.snowmoon.com (HELO localhost) (127.0.0.1) by localhost.snowmoon.com with SMTP; 27 Mar 2003 18:44:05 -0000 Date: Thu, 27 Mar 2003 13:44:05 -0500 (EST) From: Jaime To: James Earl In-Reply-To: <20030327183154.GA622@comp4.ici.net> Message-ID: <20030327133436.I60255-100000@malkav.snowmoon.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Spam-Status: No, hits=-10.7 required=5.0 tests=AWL,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, RCVD_IN_NJABL,REPLY_WITH_QUOTES,X_NJABL_OPEN_PROXY autolearn=ham version=2.50 X-Spam-Level: X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) cc: freebsd-questions@freebsd.org Subject: Re: Reverse DNS and single IP address space X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 27 Mar 2003 18:44:11 -0000 On Thu, 27 Mar 2003, James Earl wrote: > Or, do I even need to worry about reverse DNS entries since my ISP > already has them setup? They have probably done the reverse lookup already. IIRC, the reverse DNS for a single IP address can not be handed off to you by the ISP without some interesting tricks. The ISP that my job uses allowed us to do reverse DNS for our 16 IPs, but they did some interesting tricks with CNAME records to do it. The catch of this is that the reverse and forward lookups are unlikely to match. For example, you might want www.example.com --> 1.2.3.4 and 4.3.2.1.in-addr.arpa --> www.example.com. However, the ISP has already set up 4.3.2.1.in-addr.arpa --> customer15.dialup.isp.com. This would mean that your DNS wouldn't be www.example.com-->1.2.3.4-->www.example.com (as it should be) but would be www.example.com-->1.2.3.4-->customer15.dialup.isp.com. This isn't tragic in most situations, but its not perfect. Talk to your ISP for details. Good luck, Jaime