How do I check what DNS server I'm using (on Mac OS X)
You could try issuing a scutil --dns | grep 'nameserver\[[0-9]*\]' at the command line. Should give you a list of DNS servers configured on your system.
Your router is acting as a DNS forwarder, you ask your router and your router asks a DNS server for you. You need to login to your router web config to figure out what it's using, or you could just enter it directly into your Network configuration.
Use the following command to view your DNS server in Mac OS X :
Open the terminal and type
$ cat /etc/resolv.conf
to view your DNS server.
$ cat /etc/resolv.conf
domain http://www.example.com (Here, you can see DNS records info of the particular domain name.)
nameserver 68.87.85.98
nameserver 68.87.69.146