N10-005 · Question #626
Which of the following default ports would need to be disabled to block TFTP traffic?
The correct answer is C. 69. TFTP (Trivial File Transfer Protocol) uses UDP port 69 by default, so blocking port 69 is required to prevent TFTP traffic.
Question
Which of the following default ports would need to be disabled to block TFTP traffic?
Options
- A20
- B21
- C69
- D123
How the community answered
(22 responses)- A5% (1)
- B5% (1)
- C91% (20)
Why each option
TFTP (Trivial File Transfer Protocol) uses UDP port 69 by default, so blocking port 69 is required to prevent TFTP traffic.
Port 20 is the data transfer port for active mode FTP (File Transfer Protocol), not TFTP.
Port 21 is the FTP control connection port used for commands and authentication in FTP sessions, not TFTP.
TFTP is defined in RFC 1350 and operates over UDP port 69. It is commonly used for transferring configuration files to network devices or booting diskless clients. Blocking UDP port 69 on a firewall or ACL will prevent TFTP sessions from being established.
Port 123 is used by NTP (Network Time Protocol) for time synchronization between network devices, not TFTP.
Concept tested: TFTP default port number (UDP 69)
Source: https://www.rfc-editor.org/rfc/rfc1350
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