Recently, one of my ISPs DNS servers got into trouble. To quote the support desk personnel it "wasn't completely down so connections were just infinitely slow". My application was down for a couple of hours, as it couldn't connect to critical services on other machines.
While I have redundant DNS servers in my
/etc/resolv.conf file, it appears that this slowness wasn't enough for the DNS client to declare the DNS server is down, and to fallback to a secondary DNS server.
I fear this sort of problem could strike again, so I have been reading up on Ubuntu DNS configuration. There appears to be a timeout option with a default of 5 seconds, but that doesn't seem to have worked here.
Q1: Is there a log file where I can see the DNS attempts and confirm my understanding that the timeouts didn't trigger?
Q2: What do I need to do to implement such timeouts, and protect myself from such DNS issues again?
For the record, my
/etc/resolv.conf file (expurgated):
search localhost nameserver IP.addr.ess.1 nameserver IP.addr.ess.2 nameserver IP.addr.ess.3
I'm running Ubuntu 9.10 (Yeah, yeah, I hope to get a quiet period in December to upgrade.)