From owner-freebsd-isp Fri Aug 21 17:17:52 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id RAA20692 for freebsd-isp-outgoing; Fri, 21 Aug 1998 17:17:52 -0700 (PDT) (envelope-from owner-freebsd-isp@FreeBSD.ORG) Received: from redfish.go2net.com (redfish.go2net.com [207.178.55.5]) by hub.freebsd.org (8.8.8/8.8.8) with SMTP id RAA20677; Fri, 21 Aug 1998 17:17:48 -0700 (PDT) (envelope-from marcs@go2net.com) Received: from marcs by redfish.go2net.com with smtp (Exim 1.82 #2) id 0zA1M2-0007Cw-00; Fri, 21 Aug 1998 17:16:26 -0700 Date: Fri, 21 Aug 1998 17:16:25 -0700 (PDT) From: Marc Slemko X-Sender: marcs@redfish To: "Jonathan M. Bresler" cc: isp@hub.freebsd.org Subject: Re: [Q] what happens when 1 of N nameservers dies? In-Reply-To: <199808212326.QAA13587@hub.freebsd.org> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-isp@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org On Fri, 21 Aug 1998, Jonathan M. Bresler wrote: > what happens when a domain with N nameservers loses one? > > let abc.org have 3 domain nameservers ns1.abc.org, ns2.abc.org, > and ns3.abc.org. all are pointed to by the Internic. > one dies. a person/program at another domain does a lookup > on a host in abc.org. > > what happens? > > do 1/3 of the lookups return "host unknown"? No. > does the resolver try one nameserver and if it does not > receive a response try another? Yes. 1/3rd of the queries will pick that nameserver, try it, timeout, then try another. There will be delays but no false negatives unless timeouts are too short on the clients. There will actually be some weighting done with many name servers so it doesn't keep trying the one that is down time after time, but that is just optimization. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-isp" in the body of the message