The registry provides a standard WHOIS server. This can be queried on port 43 using almost any WHOIS client.
Recent WHOIS clients know how to find our WHOIS servers without you needing to know the hostname of the WHOIS server.
If, however, you have an old system or have some other need to specifiy the WHOIS server explicitly you should use the hostname "whois.TLD" as the server address (where you should replace 'TLD' with the top-level domain for the domain you wish to query).
e.g.
$ whois -h whois.gg example.gg
$ whois -h whois.je example.je
$ whois -h whois.as example.as
Please note that it is not ever permitted to query these servers using automated processes. If you want to provide a WHOIS service on your website, you must have our written permission and comply with our technical requirements.