Date: Fri, 21 Aug 1998 20:04:48 -0400 (EDT) From: jack <jack@germanium.xtalwind.net> 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.BSF.4.02.9808211950150.15050-100000@germanium.xtalwind.net> 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?
A sysadmin at that domain has some work to do. :)
> 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?
Assuming abc.org has their servers configured correctly,
everything works as usual.
Looking at a `typical' whois listing :)
germanium# whois freebsd.org
[snip]
Domain servers in listed order:
WHO.CDROM.COM 204.216.27.3
NS1.CRL.COM 165.113.1.36
NS2.CRL.COM 165.113.1.37
NS1.IAFRICA.COM 196.7.0.139
NS2.IAFRICA.COM 196.7.142.133
WHO.CDROM.COM is configured as the primary server for the domain,
all others are configured as secondary servers.
When a DNS server at someother.domain wants to find
www.freebsd.org's IP address it will first query WHO.CDROM.COM,
if that fails it will try NS1.CRL.COM, if that also fails it will
try NS2.CRL.COM, if that fails .....
> do 1/3 of the lookups return "host unknown"?
No. All but the primary server are configured as secondaries and
update from the primary periodically. They each have a `full
listing' for the domain[s] they serve.
> does the resolver try one nameserver and if it does not
> receive a response try another?
Yes, in "listed order".
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