How to Setup Opendns In Mac Os X ?
Instead of using your ISP DNS service, you can try free DNS services such as OpenDNS or Google Public DNS to solve ISP specific connection problems.
How to Setup 
in Windows Mac OS X
- Go to System Preferences.
- Click on Network.
- Select your internet connection in your list and click Advanced.
- Select the DNS tab and add 208.67.222.222 and 208.67.220.220 to the list of DNS servers.
- Click OK
For Google Public DNS Enter 8.8.8.8 and 8.8.4.4 in 4th step.