GSEC · Question #168
Which of the following ports is the default port for Layer 2 Tunneling Protocol (L2TP)?
The correct answer is D. UDP port 1701. L2TP uses UDP port 1701 as its default transport port, a fact defined in its original RFC specification.
Question
Which of the following ports is the default port for Layer 2 Tunneling Protocol (L2TP)?
Options
- ATCP port 443
- BUDP port 161
- CTCP port 110
- DUDP port 1701
How the community answered
(26 responses)- A4% (1)
- B15% (4)
- C8% (2)
- D73% (19)
Why each option
L2TP uses UDP port 1701 as its default transport port, a fact defined in its original RFC specification.
TCP port 443 is reserved for HTTPS - secure web traffic over TLS/SSL - and is not associated with L2TP.
UDP port 161 is used by SNMP (Simple Network Management Protocol) for polling and managing network devices, not for L2TP tunneling.
TCP port 110 is the default port for POP3 (Post Office Protocol version 3), which is used to retrieve email from a mail server.
L2TP (Layer 2 Tunneling Protocol), standardized in RFC 2661, operates over UDP port 1701. UDP is used rather than TCP because L2TP encapsulates PPP frames and delegates reliability and error correction to the encapsulated protocols, making the lower overhead of UDP preferable for tunneling.
Concept tested: L2TP default UDP port 1701 assignment
Source: https://www.rfc-editor.org/rfc/rfc2661
Topics
Community Discussion
No community discussion yet for this question.