(caching) DNS intermittent timeouts

overlord73 · 02-26-2014, 01:39 AM

Hi,

we have a caching named and squid-proxy on COS6.4 running in our DMZ. Since a few days we noticed some DNS timeouts

I found some issues about DNS queries with squid:
http://floriancrouzat.net/2013/05/ce...iss503-errors/

I tried the newly build with the mentioned option "dns_v4_first on", but no improvements.
I further tested other external DNS-Servers in the resolv.conf....but again and again timeouts.

A simple nslookup works and a short time later:
;; connection timed out; trying next origin
;; connection timed out; no servers could be reached

Seems that named is the problem, not squid!?

Any help will be welcome....

nini09 · 02-26-2014, 02:27 PM

You can try following option.
It seems that glibc implements a timeout to handle broken DNS servers (or firewalls) that can't handle a parallel lookup of IPv4 and IPv6 addresses. The following workarounds might help:

- run dnsmasq
- run nscd
- add 'options single-request' to /etc/resolv.conf