Query name server(s) for various domain records.

# To query your system's default name server for an IP address (A record) of the domain:
nslookup example.com

# To query a given name server for a NS record of the domain:
nslookup -type=NS example.com 8.8.8.8

# To query for a reverse lookup (PTR record) of an IP address:
nslookup -type=PTR 54.240.162.118

# To query for ANY available records using TCP protocol:
nslookup -vc -type=ANY example.com

# To query a given name server for the whole zone file (zone transfer) of the domain using TCP protocol:
nslookup -vc -type=AXFR example.com name_server

# To query for a mail server (MX record) of the domain, showing details of the transaction:
nslookup -type=MX -debug example.com

# To query a given name server on a specific port number for a TXT record of the domain:
nslookup -port=port_number -type=TXT example.com name_server