Can't connect to internet with Norton DNS

I have a broadband connection (not wifi, but one with wire).  I connect the internet after logging from ISP site (www.reliancebroadband.co.in).  Till now I was keeping the IP and DNS numbers blank. 
 
Now when I enter Norton DNS numbers, then at that time the internet works, but when I restart laptop next day then I am unable to open ISP or any other site.  Once I again keep the DNS numbers blank then I am able to login.
 
I have ZTE ZXDSL 831 II modem.  I tried many IP address (posted on net) to configure it... also the Default Gateway one through IPCONFIG, but I am not able to get any configuration page.
 
Plz suggest.