Need to know which port to be blocked in my local machine so that the nslookup on A record doesnot work? To know the above i need to understand how the lookup on A record how does the request go from the local machine (port) to the nameservers/ rootservers?

For example: C:> nslookup -type=a google.com

Server: MyDslModem.local.lan Address: 192.168.1.1

Non-authoritative answer: Name: google.com Address: 209.85.231.104

Here which from which local port from the local machine does the lookup starts from?