Slow DNS response times if one DNS server is down
First post and just joined - so be kind J
I'm totally new to Ubuntu / Linux.
Let me give an overview of the setup first.
About 60 Ubuntu 12.04 servers (64 bit) split across 2 sites. Most of the machines are VM's. Static IP addresses assigned and all servers are "kerberized". All servers are non-gui and each site has 1 dns server. All but 4 servers were 10.04 and recently upgraded to 12.04 LTS. The 4 servers are clean install of 12.04.
As part of DR testing, I bring one of the DNS servers down from one site and check how long it will take to resolve addresses across the sites.
It can take about 30-50 secs for it starting to ping a device on the network. I have been looking at various sites and had a few discussions here at work, but not really getting much as I don’t have depth understanding of Linux.
I have looked at the resolv.conf file and there it has entries of the 2 DNS servers. After research, I found if I put the line of “option timeout:1” it actually works. The response times are dramatically improved. But then I was told that in 12.04 version, the resolv.conf gets over written and shouldn’t be edited. I saw many sites referring to this, but their resolution is to put the data in tail, head and base files in /etc/resolvconf/resolv.conf.d. But when I check the upgraded servers, there is no folder.
I did do a test where I wiped the settings in resolv.conf file and restarted the server to see if the settings get populated, but they didn’t. Also in the clean install of 12.04, in the resolv.conf file you see the following
“# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN”
Where as in the upgraded boxes, there is nothing.
I convinced myself that the solution of amending the resolv.conf was correct one until I was told not to touch it.
Can some one please help me in either finding the correct solution of if one dns server goes down, the response times are acceptable or if I was going down the correct route? Ive seen resolvconf dameon, dnsmarq and others but not exactly sure what they are or how they could be used.
Many thanks in advance for your help
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