220-1101 Question 70
Single answer445 – Server Message Block (SMB)/Common Internet File System (CIFS)A technician is setting up a new Windows 11 workstation in a small office. The user can browse websites and access email, but cannot open a shared folder on a file server by typing \FILESRV01\Accounting. The technician confirms the workstation can ping FILESRV01 by name and IP address. The file server team reports the share is online and other users can access it. Which port is MOST likely being blocked between the workstation and the file server?
- A
TCP 21
- B
TCP 23
- C
TCP 445
- D
TCP 3389
Show answer and explanation
Correct answer: C
Explanation
The best answer is TCP 445 because Server Message Block (SMB), historically associated with CIFS in older Microsoft networking contexts, uses TCP port 445 on modern Windows networks. Accessing a shared folder with a UNC path such as \server\share relies on SMB, not web, email, FTP, Telnet, or RDP services. In this scenario, successful pings by name and IP suggest that basic IP connectivity and name resolution are functioning. Since the server team confirms the share is available and other users can access it, the most likely remaining issue is a local or network firewall blocking SMB traffic from this workstation. Microsoft networking documentation and standard port references consistently identify TCP 445 as the primary port for SMB over TCP/IP.
- A. Incorrect.
TCP 21 is used for FTP control connections, not for standard Windows file sharing. A user trying to access a UNC path such as \FILESRV01\Accounting is using SMB/CIFS rather than FTP. Someone might choose this option because FTP also transfers files, but it is not the protocol used for Windows shared folders.
- B. Incorrect.
TCP 23 is used for Telnet, which provides remote command-line access and is considered insecure. It is unrelated to normal access to a Windows network share. This distractor targets the misconception that any remote-access port could affect file shares.
- C. Correct.
TCP 445 is correct. Modern Windows systems use SMB directly over TCP/IP on port 445 for shared folders, printers, and related file-sharing functions. If DNS/name resolution works and the server is reachable by ping, but UNC share access fails while other users can still connect, a blocked SMB port is the most likely issue.
- D. Incorrect.
TCP 3389 is used by Remote Desktop Protocol (RDP) for remote GUI access to a Windows system. Blocking RDP would prevent remote desktop sessions, but it would not specifically stop access to a shared folder over SMB. This is a plausible distractor because both involve connecting to a remote Windows host.