Thanks for replying.
Error message in firefox :
Server not found
Firefox can't find the server at {domain name}.
Yes, the nameservers for .net are correct. The same nameservers are being used for .net and .com (which is working sometimes and sometimes redirecting to parking page; probably because nameservers were updated recently) and .net (which isn't working).
As per intodns.com, for .net :
Domain NS records - All found
DNS Parent sent Glue The parent nameserver b1.in.afilias-nst.in is not sending out GLUE for every nameservers listed, meaning he is sending out your nameservers host names without sending the A records of those nameservers. It's ok but you have to know that this will require an extra A lookup that can delay a little the connections to your site. This happens a lot if you have nameservers on different TLD (domain.com for example with nameserver ns.domain.org.)
Nameservers A records Good. Every nameserver listed has A records. This is a must if you want to be found.
MX MX Records Oh well, I did not detect any MX records so you probably don't have any and if you know you should have then they may be missing at your nameservers!
WWW Error WWW A Record ERROR: I could not get any A records for {domain}!
(I only do a cache request, if you recently added a WWW A record, it might not show up here.)