bind-8.2.3-0.6.x (used as caching DNS) often gets to such state that it stops resolving SOME hostnames. -------------------------------- dig www.clickxchange.com a ; <<>> DiG 8.3 <<>> www.clickxchange.com a ;; res options: init recurs defnam dnsrch ;; res_nsend to server default -- 192.168.3.1: Connection timed out Stange thing is that dig clickxchange.com a works OK. Only www.clickxchange.com can not be resolved. Any other host names are OK dig www.redhat.com a ; <<>> DiG 8.3 <<>> www.redhat.com a ;; res options: init recurs defnam dnsrch ;; got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 4 ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 3, ADDITIONAL: 3 ;; QUERY SECTION: ;; www.redhat.com, type = A, class = IN ;; ANSWER SECTION: www.redhat.com. 1D IN A 216.148.218.197 www.redhat.com. 1D IN A 216.148.218.195 ------------------------------- The restart of bind fixes the problem: dig www.clickxchange.com a ; <<>> DiG 8.3 <<>> www.clickxchange.com a ;; res options: init recurs defnam dnsrch ;; got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 4 ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 2, ADDITIONAL: 2 ;; QUERY SECTION: ;; www.clickxchange.com, type = A, class = IN ;; ANSWER SECTION: www.clickxchange.com. 1D IN CNAME clickxchange.com. clickxchange.com. 1D IN A 216.115.239.51 --------------------------- There is no any bind-related error messages in /var/log/messages I reported this problem a while ago, in bind 8.1.* but as you can see from the logs above the problem still exists in Bind 8.2.3
This is a link to that old bug: http://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=10479
This looks like the uplink DNS (clickxchange.com) was down, the result "domain doesn't exist" got cached, and was looked up from the cache later - in that case, it should work again a day later. Could this be the problem?
I do not think that this was the cause because dig www.clickxchange.com a took several seconds to reply. If it were cached it would reply right away. For all cached domains the DNS at 192.168.3.1 replies with no any delay.
Also, in the response from dig www.clickxchange.com a there was a string having "Connection timed out" ;; res_nsend to server default -- 192.168.3.1: Connection timed out which seems means that caching DNS at 192.168.3.1 did not send a response in specific time period.