From owner-freebsd-net@FreeBSD.ORG Sun May 1 05:09:14 2011 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 7A828106746E for ; Sun, 1 May 2011 05:08:55 +0000 (UTC) (envelope-from bakul@bitblocks.com) Received: from mail.bitblocks.com (ns1.bitblocks.com [173.228.5.8]) by mx1.freebsd.org (Postfix) with ESMTP id 649A08FC1A for ; Sun, 1 May 2011 05:08:55 +0000 (UTC) Received: from silver.bitblocks.com (silver.bitblocks.com [192.168.125.2]) by mail.bitblocks.com (Postfix) with ESMTP id 08802B827 for ; Sat, 30 Apr 2011 22:08:55 -0700 (PDT) From: Bakul Shah Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Date: Sat, 30 Apr 2011 22:08:54 -0700 Message-Id: <466DA43B-EFF4-45DB-83C7-D6DD2B86CB35@bitblocks.com> To: freebsd-net@freebsd.org Mime-Version: 1.0 (Apple Message framework v1084) X-Mailer: Apple Mail (2.1084) Subject: Strange DNS problem X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 01 May 2011 05:09:14 -0000 I am running a local dns server (bind9). It works ok for the most part but a number of domains do not resolve and I have not been able to detect any pattern. For instance $ host weather.com=20 Host weather.com not found: 3(NXDOMAIN) Here is the tcpdump output (on the internal side): 21:45:14.662220 IP 192.168.125.253.20204 > 192.168.125.9.53: 16136+ A? = weather.com. (29) 21:45:14.662696 IP 192.168.125.9.53 > 192.168.125.253.20204: 16136 = ServFail 0/0/0 (29) 21:45:14.663090 IP 192.168.125.253.59705 > 192.168.125.9.53: 4383+ A? = weather.com.bitblocks.com. (43) 21:45:14.663193 IP 192.168.125.9.53 > 192.168.125.253.59705: 4383 = NXDomain* 0/1/0 (94) What is strange is *nothing* goes out of my network when such a failure occurs! [My gateway machine does NAT on the internal side but the symptom is the same on the gateway machine] I ignored the problem for a while but recently I noticed a few more domains do not resolve! May be nothing has changed since I didn't try these domains before. This is on 8.2-release (but the symptom was the same with 8.1 and may be earlier). I checked named.conf and AFAIK it seems ok -- it has not changed substantially since 2006 (I moved to a different IP block and had to change my ISP's dns server address -- it is my secondary). I'd appreciate any hints on how to diagnose this. Thansks!