This CISSP practice question tests your understanding of communication and network security. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A network engineer is troubleshooting an IPsec VPN tunnel between two sites. The tunnel is established but no traffic is passing. Which command should the engineer use to verify the phase 2 security associations?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "which command"
Why it matters: Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
Traceroute between site gateways
Why wrong: Traceroute shows path but doesn't verify IPsec SAs.
show crypto ipsec sa
This command displays phase 2 SAs.
Ping between site gateways
Why wrong: Ping checks connectivity but not VPN tunnel state.
show crypto isakmp sa
Why wrong: This shows phase 1 SAs, not phase 2.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
show crypto ipsec sa
The command 'show crypto ipsec sa' displays the IPsec security associations (SAs) for Phase 2, which include encryption and authentication parameters, SPI values, and packet counters. Since the tunnel is established but no traffic passes, this command reveals whether the Phase 2 SAs are properly negotiated and active, or if they are in a mismatch state (e.g., mismatched proxy IDs or transform sets).
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Traceroute between site gateways
Why it's wrong here
Traceroute shows path but doesn't verify IPsec SAs.
show crypto ipsec sa
Why this is correct
This command displays phase 2 SAs.
Clue confirmation
The clue word "which command" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Ping between site gateways
Why it's wrong here
Ping checks connectivity but not VPN tunnel state.
show crypto isakmp sa
Why it's wrong here
This shows phase 1 SAs, not phase 2.
Common exam traps
ISC2 often tests the distinction between Phase 1 (IKE) and Phase 2 (IPsec) SAs, leading candidates to mistakenly choose 'show crypto isakmp sa' when the question specifically asks about Phase 2 security associations.
Trap categories for this question
Command / output trap
Traceroute shows path but doesn't verify IPsec SAs.
Detailed technical explanation
IPsec Phase 2 uses the IKE (Internet Key Exchange) protocol to negotiate SAs for ESP or AH, including encryption algorithms (e.g., AES-256) and integrity checks (e.g., SHA-256). The 'show crypto ipsec sa' output includes per-peer SA details, such as the number of packets encrypted/decrypted, which helps identify if traffic is being dropped due to SA expiry, mismatched proxy IDs, or anti-replay window issues. In real-world scenarios, a common cause of 'tunnel up, no traffic' is a mismatch in the interesting traffic (ACL) definition between peers.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A developer is choosing between AES-256 (symmetric) and RSA-2048 (asymmetric) for encrypting a large file that will be sent to a partner. Symmetric encryption is fast but requires key exchange; asymmetric is slower but solves the key distribution problem. A hybrid approach — encrypt the file with AES, encrypt the AES key with RSA — is standard. Questions like this test whether you understand when each approach applies.
What to study next
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Communication and Network Security — This question tests Communication and Network Security — Read the scenario before looking for a memorised answer..
The correct answer is: show crypto ipsec sa — The command 'show crypto ipsec sa' displays the IPsec security associations (SAs) for Phase 2, which include encryption and authentication parameters, SPI values, and packet counters. Since the tunnel is established but no traffic passes, this command reveals whether the Phase 2 SAs are properly negotiated and active, or if they are in a mismatch state (e.g., mismatched proxy IDs or transform sets).
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "which command". Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
This CISSP practice question is part of Courseiva's free ISC2 certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CISSP exam.
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