Date: Fri, 21 Aug 1998 17:16:25 -0700 (PDT) From: Marc Slemko <marcs@znep.com> To: "Jonathan M. Bresler" <jmb@FreeBSD.ORG> Cc: isp@hub.freebsd.org Subject: Re: [Q] what happens when 1 of N nameservers dies? Message-ID: <Pine.GSO.4.02A.9808211715110.12882-100000@redfish> In-Reply-To: <199808212326.QAA13587@hub.freebsd.org>
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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
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