Date: Thu, 21 Oct 2010 06:22:15 -0500 From: Martin McCormick <martin@dc.cis.okstate.edu> To: freebsd-questions@freebsd.org Subject: How FreeBSD Handles a DNS that is Down Message-ID: <201010211122.o9LBMFa2063759@x.it.okstate.edu>
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This is an extremely novice question on my part, but after what I recently witnessed, I am not so sure I understand all I know. The normal procedure on internet-connected systems is to set the resolv.conf file to include at least 2 domain name servers. Example: nameserver 139.78.100.1 nameserver 139.78.200.1 Last night, I had to take down our primary DNS for maintenance and lots of systems began having trouble of various kinds. While I expected the FreeBSD system I was on to hang for a couple of seconds and then start using the second DNS, it basically froze while some Linux boxes also began exhibiting similar behavior. I finally manually changed the resolv.conf on the system I was using to force the slave DNS to be first in the list and that helped, but loosing the primary DNS was not the slight slowdown one might expect. It was a full-blown outage. Are we missing some other configuration directive for Unix systems that would make the systems use the redundancy a little more gracefully than what happened? Otherwise, why have it if somebody has to manually intervene? The only thing we should have lost was dynamic updates. The systems that I know that were basically hosed were FreeBSD and Linux. As soon as the mother ship came back on line, everything was sweetness and light. Thanks for any thoughts on this issue. I have only been running DNS for around 18 years and we fortunately do not get to see this condition often and when we do, it's hopefully for very short periods, but the disruption is total. Martin McCormick WB5AGZ Stillwater, OK Systems Engineer OSU Information Technology Department Telecommunications Services Group
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