CREST Practitioner Security Analyst (CPSA) Practice

What type of services does Port 138 (UDP) support?

1. NetBIOS (name services)

2. Simple Network Management Protocol

3. NetBIOS (datagram services)

4. File Transfer Protocol

The correct answer is: NetBIOS (datagram services)

Port 138 (UDP) is associated with NetBIOS datagram services. This service is used for sending connectionless datagrams over a local area network (LAN) to allow applications to communicate without establishing a formal connection, which is why it fits into the context of those services. Specifically, it is part of the NetBIOS over TCP/IP suite, which facilitates applications on different computers to communicate within a local network environment. NetBIOS datagram services allow for functions such as name resolution and sending messages between hosts without requiring a dedicated connection, making it ideal for network setups where quick, connectionless communication is needed. This is particularly useful in smaller networks or when interacting with legacy systems that still rely on the NetBIOS protocol. In contrast, the other options pertain to different services or protocols: name services for NetBIOS function on port 137, while the Simple Network Management Protocol operates over port 161, and File Transfer Protocol typically uses ports 21 (control) and 20 (data). Thus, the association of UDP port 138 with NetBIOS datagram services makes it the correct choice in this context.