A new vulnerability in the SMB protocol on the Windows systems was recently discovered, but...

To protect the servers in the company’s DMZ from external attack due to the new vulnerability in the SMB protocol on the Windows systems, the security administrator should block TCP ports 139 and 445 for all external inbound connections to the DMZ.

SMB uses TCP port 139 and 445. Blocking these ports will prevent external attackers from exploiting the vulnerability in SMB protocol on Windows systems.

Blocking TCP ports 139 and 445 for all external inbound connections to the DMZ can help protect the servers, as these ports are used by SMB protocol. Port 135 is also associated with SMB, but it is not commonly used. Ports 143 and 161 are associated with other protocols and services. Reference: CompTIA Security+ Certification Exam Objectives, Exam SY0-601, 1.4 Compare and contrast network architecture and technologies.