It seems ur exams r over!
In mtnl rs.949 plan u get a static IP only!
Goto system>administration>"networking" and u get to configure everything!
For dns, type 192.168.1.1 in ur browser window (if u have mtnl/dlink router to get inside of ur routers settings) and copy the dns servers from there to ur list in "networking" window into the DNS section! OR u can goto
http://www.opennic.unrated.net/public_servers.html , and get a dns or two.
Sometimes ISP's dns servers communication rate totally sucks, then its better to use public dns servers! Since the whole world uses mostly the class c IP addresses, therefore the subnet mask is 255.255.255.0.
After ur done, save ur settings and restart the network from that "network" window only. Just disable it and enable it again! Ur done !