Which port does the Whois service use?

Which port does the Whois service use?

• A. 43
• B. 110
• C. 25
• D. 173

Answer: (A)

The main idea here is identifying the standard network port used by the WHOIS service. WHOIS is a simple query protocol that retrieves domain registration data, and it traditionally runs over TCP on port 43. When you query a WHOIS server, you connect to that server on port 43, send the domain name, and receive the registration details in plain text. The other ports listed are for completely different services: port 110 is used for POP3 email retrieval, port 25 for SMTP email sending, and port 173 is not a standard port associated with WHOIS. Since WHOIS is defined to listen on port 43, that port is the correct choice.

The main idea here is identifying the standard network port used by the WHOIS service. WHOIS is a simple query protocol that retrieves domain registration data, and it traditionally runs over TCP on port 43. When you query a WHOIS server, you connect to that server on port 43, send the domain name, and receive the registration details in plain text. The other ports listed are for completely different services: port 110 is used for POP3 email retrieval, port 25 for SMTP email sending, and port 173 is not a standard port associated with WHOIS. Since WHOIS is defined to listen on port 43, that port is the correct choice.