Wednesday, January 28, 2009

BSNL DNS Internet access disrupted yet Skype is functional

Users of BSNL might encounter this issue quite often.
No website can be opened using Internet Explorer, Firefox, Chrome, etc. Yahoo Messenger wont work too.
But Skype works without a problem.

The reason :
The DNS server of BSNL doesn't work for some reason. Each website that you try to access eg. www.neooug.org gets translated to an IP address. This translation is provided by the DNS server. And if the DNS server is unavailable, your computer doesn't get back an IP address and hence you are unable to access the website.
But if you try to access the website using the IP address directly ( On command prompt : ping www.yahoo.com
gives you
H:\>ping www.yahoo.com

Pinging www.yahoo-ht3.akadns.net [69.147.76.15] with 32 bytes of data:

Reply from 69.147.76.15: bytes=32 time=10ms TTL=54
Reply from 69.147.76.15: bytes=32 time=10ms TTL=54
Reply from 69.147.76.15: bytes=32 time=10ms TTL=54
Reply from 69.147.76.15: bytes=32 time=16ms TTL=54

Ping statistics for 69.147.76.15:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 10ms, Maximum = 16ms, Average = 11ms

So, if you put http://69.147.76.15/ in the web-browser, you can access the website. But its just not possible to get the IP address if the DNS server is down.
In case of Skype, this issue doesn't arise because skype connects using the IP address.

Solution:
Open the Network Connection/Wireless connection properties on your computer. Open Properties for TCP/IP and change the "Obtain DNS server address automatically" to "Use the following DNS Server addresses"


208.67.222.222
and 
208.67.220.220

These addresses are provided by http://www.opendns.com

You can also configure your wireless router to use this address so that you don't have to configure each machine on your network to set this DNS information.

More instructions can be found at

https://www.opendns.com/smb/start