CREST Practitioner Security Analyst (CPSA) 2025 – 400 Free Practice Questions to Pass the Exam

The protocol assigned to port 43 is WHOIS. WHOIS is a query and response protocol that is used to obtain information about domain names and IP address allocations. When a WHOIS query is made, the server sends back information about the domain's registration details, including the name of the registrant, contact information, and the status of the domain. This protocol is crucial for network administrators and cybersecurity professionals for tasks such as tracking down domain ownership and managing domain records.

In contrast, the other protocols mentioned use different ports: POP3 (Post Office Protocol version 3) and IMAP (Internet Message Access Protocol) are used for retrieving emails and typically operate on ports 110 and 143, respectively. SNMP (Simple Network Management Protocol) is utilized for managing devices on IP networks, commonly using port 161. Therefore, the assignment of port 43 specifically corresponds to the WHOIS protocol, making it the correct answer.