When I say speed up your connection I do not mean the download speed but it is for the browsing experience we get. It takes some time for the DNS to respond when we try to reach a web address as the DNS would find out for you what IP address to reach and where the server is located. Once your system has this info it starts direct communication with the web server of whatever website you are trying to open.
This process should ideally take less then 20-30ms but using BSNL DNS would mean that you would be waiting some 2-3 seconds some times at peak hours for the DNS to respond as their servers are over loaded in the evenings when the whole nation descends upon the world wide web all at once when they get home from work.
I use Google's DNS for this purpose and if you check the latency to their servers is normally 8-10ms from anywhere in India. Don't blame Google if you are on a lousy GPRS class 5 connection. Generally speaking on a decent wired connection that is the latency you should ideally get.
Below are the IP addresses for Google DNS that you can use to speed things up for yourself :
It does not matter which ISP you use because you could still use a third party DNS. Some people use Open DNS but I find Google DNS to be the best out of the lot.
I hope this helps.