H12-725_V4.0 · Question #106
ESP (Encapsulating Security Payload) is a protocol of IPSec that is used to provide confidentiality and anti-replay services for IP, including confidentiality of data packet content and limited…
The correct answer is D. 50. ESP is assigned IP protocol number 50 by IANA, which is how the IP layer identifies and hands off ESP-encapsulated packets to the correct handler - making D correct. Option B (51) is the protocol number for AH (Authentication Header), ESP's sibling IPSec protocol that provides…
Question
ESP (Encapsulating Security Payload) is a protocol of IPSec that is used to provide confidentiality and anti-replay services for IP, including confidentiality of data packet content and limited traffic confidentiality. Which of the following is the protocol number of ESP?
Options
- A500
- B51
- C4500
- D50
How the community answered
(20 responses)- A5% (1)
- C10% (2)
- D85% (17)
Explanation
ESP is assigned IP protocol number 50 by IANA, which is how the IP layer identifies and hands off ESP-encapsulated packets to the correct handler - making D correct. Option B (51) is the protocol number for AH (Authentication Header), ESP's sibling IPSec protocol that provides integrity and authentication but not confidentiality. Options A (500) and C (4500) are UDP port numbers, not protocol numbers: 500 is used by IKE (Internet Key Exchange) for IPSec session negotiation, and 4500 is used for NAT-T (NAT Traversal) when IPSec traffic must pass through a NAT device. Memory tip: think "ESP = 50, AH = 51" - they're consecutive numbers, E comes before A in the alphabet, and 50 comes before 51.
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