You can easily check it by WHOIS:

$ whois dev.
% IANA WHOIS server
% for more information on IANA, visit http://www.iana.org/
% This query returned 1 object

domain:       DEV

organisation: Charleston Road Registry Inc.
address:      1600 Amphitheatre Parkway
address:      Mountain View CA 94043
address:      United States of America (the)

# the rest of output omitted

And some hints give Wikipedia: List of Internet top-level domains.