The options are as follows:
-a Use the American Registry for Internet Numbers (ARIN) database.
It contains network numbers used in those parts of the world cov-
ered neither by APNIC nor by RIPE.
(Hint: All point of contact handles in the ARIN whois database
end with "-ARIN".)
-A Use the Asia/Pacific Network Information Center (APNIC) database.
It contains network numbers used in East Asia, Australia, New
Zealand, and the Pacific islands.
-b Use the Network Abuse Clearinghouse database. It contains
addresses to which network abuse should be reported, indexed by
domain name.
-c country-code
This is the equivalent of using the -h option with an argument of
"country-code.whois-servers.net".
-d Use the US Department of Defense database. It contains points of
contact for subdomains of .MIL.