(ISC)2 Certified in Cybersecurity Practice Exam

Ports 137, 138, and 139 are associated with the NetBIOS protocol, which is primarily used for communication over local networks. Specifically, these ports serve the following functions:

- Port 137 is used for NetBIOS Name Service, which is critical for the registration and resolution of NetBIOS names to IP addresses. This facilitates the identification of devices on a local area network (LAN).

- Port 138 is employed for NetBIOS Datagram Service, which supports the transmission of datagram messages between networked computers. This is helpful for services that require connectionless communication.

- Port 139 is used for NetBIOS Session Service, allowing ordered and reliable data communication between computers. This is typically utilized by applications that require a connection-oriented protocol, such as file sharing over networks.

These ports are integral to the functioning of NetBIOS, enabling services like file and printer sharing in Windows networks. Understanding the role of these ports is fundamental for network management and security, as they can also be potential vectors for various types of cyber threats if left unsecured or poorly managed.