DNS Redundancy After a Disaster

Martin McCormick martin at dc.cis.okstate.edu
Tue Jan 24 02:41:06 UTC 2006


	In discussing various disaster scenarios, we have been thinking
of what we would need to do if some mammoth event destroyed most of our
infrastructure on our campus, rendering our local master and slave
DNS's inoperable or inaccessible.

	One obvious solution is to install a slave in a nearby town
which will quietly mirror all the updates to all our zones and then
become a master if we need it to.

	One of the beautiful things about the DNS protocol is that one
should have one or more slaves listed along with the master.  Other
than not being able to dynamically update one's zones, how bad does
service get if the master is dead and the only working DNS is an
off-site slave?

	Do large companies do anything special to insure that if a
master DNS fails, there will always be something at the IP address of
the master?

	Our DNS's are running on FreeBSD and have a fabulous track
record for robustness so I am fortunate that we don't get to see much
in the way of failure modes, but we must 
always plan for the worst and be able to give truthful answers to the
other groups we serve.

	Thanks for any ideas, war stories, etc.

Martin McCormick WB5AGZ  Stillwater, OK 
OSU Information Technology Department Network Operations Group



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