Does it possible to check which DNS server used for resolving domain name (in intraned network)? We have many steps: proxy, BigIP, domain controllers, etc. I have a complicated networks with many DNS server. Sometimes when in browser I use:
http://mysitedomainalias.mydomain.com
I receive web page, sometime after near 15 minutes I receive error about timeout. But when I use IP address instead of domain alias I always reach my web page. So I have decided that it could be a problem with DNS server. I would like to know common way how to resolve similar problems.
On *NIX systems, dig is a standard tool to test and debug DNS servers:
deceze$ dig google.com
...
;; QUESTION SECTION:
;google.com. IN A
;; ANSWER SECTION:
google.com. 5 IN A 173.194.35.168
google.com. 5 IN A 173.194.35.161
google.com. 5 IN A 173.194.35.169
...
;; Query time: 84 msec
;; SERVER: 192.168.10.1#53(192.168.10.1)
;; WHEN: Mon Jul 14 15:59:05 2014
;; MSG SIZE rcvd: 204
In the last part, SERVER signifies which DNS server answered our request.
Some more things you can then do with dig:
query a specific DNS server instead of the system's default:
$ dig @mydns.example.com google.com
trace each step of the resolution chain to see any problems in the canonical name servers:
$ dig google.com +trace
query specific record types:
$ dig google.com NS
$ dig google.com MX
$ dig google.com ANY
See the manual: http://linux.die.net/man/1/dig