I have a class A ip address from bsnl and had been experiencing the same problem.
The problem is with the bsnl dns servers, I resolved the hostnames with bsnl dns servers and open dns and got different results.
Switching to open dns should resolve the problem.
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with bsnl dns servers
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G:\>nslookup
www.youtube.com
Server: ns1.bsnl.in
Address: 218.248.240.23
Non-authoritative answer:
Name: youtube.l.google.com
Address:
208.117.236.75
Aliases:
www.youtube.com
G:\>nslookup in.youtube.com
Server: ns1.bsnl.in
Address: 218.248.240.23
*** ns1.bsnl.in can't find in.youtube.com: Server
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with opendns
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G:\>nslookup
www.youtube.com
Server: resolver1.opendns.com
Address: 208.67.222.222
Non-authoritative answer:
Name: youtube.l.google.com
Address:
208.65.153.238
Aliases:
www.youtube.com
G:\>nslookup in.youtube.com
Server: resolver1.opendns.com
Address: 208.67.222.222
Non-authoritative answer:
Name: youtube.l.google.com
Address: 208.65.153.238
Aliases: in.youtube.com