What is the WHOIS protocol, which port does it use, and what information can be retrieved with a WHOIS lookup?

• A.WHOIS uses TCP port 43 but only for .com and .net domains; all other TLDs use different ports.
• B.WHOIS uses UDP port 43 and provides only the IP address associated with a domain name.
• C.WHOIS uses TCP port 80 and is accessed exclusively via web browsers; no command-line client exists.
• D.WHOIS uses TCP port 43. A WHOIS query returns domain registration information: registrant name/organization, registrar, registration/expiration dates, authoritative name servers, and abuse contacts. WHOIS can also query IP address ARIN/RIPE/APNIC registrations for ASN and organization details. Privacy protection (WHOIS redaction) is now common under GDPR.