Question 243 of 504
Network and Communications SecurityhardMultiple ChoiceObjective-mapped

SSCP Network and Communications Security Practice Question

This SSCP practice question tests your understanding of network and communications security. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.

Exhibit

crypto isakmp policy 10
 encr aes 256
 authentication pre-share
 group 5
 lifetime 3600
crypto ipsec transform-set AES256-SHA esp-aes 256 esp-sha-hmac
crypto map CMAP 10 ipsec-isakmp
 set peer 198.51.100.1
 set transform-set AES256-SHA
 match address 101

Refer to the exhibit. A network engineer is configuring a site-to-site VPN. The remote peer is using AES-256 encryption and SHA-1 for integrity. Which configuration parameter is likely misconfigured?

Question 1hardmultiple choice
Read the full VPN explanation →

Exhibit

crypto isakmp policy 10
 encr aes 256
 authentication pre-share
 group 5
 lifetime 3600
crypto ipsec transform-set AES256-SHA esp-aes 256 esp-sha-hmac
crypto map CMAP 10 ipsec-isakmp
 set peer 198.51.100.1
 set transform-set AES256-SHA
 match address 101

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

Group 5

The remote peer is using AES-256 encryption and SHA-1 for integrity, which are both supported in an IPsec transform-set. However, the exhibit shows that the local peer is configured with Group 5 (Diffie-Hellman 1536-bit), while the remote peer likely expects a different DH group (e.g., Group 2 or Group 14). DH group mismatch during Phase 1 (IKE) negotiation causes the VPN tunnel to fail, even if encryption and integrity algorithms match.

Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • Transform-set

    Why it's wrong here

    The transform-set uses AES-256 and SHA-1, which matches the peer.

  • Pre-shared key

    Why it's wrong here

    Pre-shared key is configured but not shown; mismatch would cause failure but is not indicated.

  • Group 5

    Why this is correct

    Group 5 (DH5) is deprecated; the peer may require a stronger DH group.

    Related concept

    Read the scenario before looking for a memorised answer.

  • IKE lifetime

    Why it's wrong here

    Lifetime mismatch can cause renegotiation issues but is not the most likely problem.

Common exam traps

Common exam trap: answer the scenario, not the keyword

ISC2 often tests the misconception that transform-set mismatches are the only cause of VPN failures, but the trap here is that DH group mismatch in IKE Phase 1 is a separate, easily overlooked parameter that prevents tunnel establishment even when encryption and integrity algorithms match.

Trap categories for this question

  • Command / output trap

    Pre-shared key is configured but not shown; mismatch would cause failure but is not indicated.

Detailed technical explanation

How to think about this question

Diffie-Hellman groups determine the strength of the key exchange during IKE Phase 1. Group 5 uses a 1536-bit modulus, while Group 2 uses 1024-bit and Group 14 uses 2048-bit. Cisco devices require identical DH groups on both peers for the IKE SA to form; a mismatch results in a 'no proposal chosen' error in debug output. In real-world scenarios, administrators often overlook DH group consistency when upgrading security policies, leading to intermittent VPN failures.

KKey Concepts to Remember

  • Read the scenario before looking for a memorised answer.
  • Find the constraint that changes the correct option.
  • Eliminate answers that are true in general but not in this case.

TExam Day Tips

  • Watch for words such as best, first, most likely and least administrative effort.
  • Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Real-world example

How this comes up in practice

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

Got this wrong? Here's your next step.

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

Questions learners often ask

What does this SSCP question test?

Network and Communications Security — This question tests Network and Communications Security — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: Group 5 — The remote peer is using AES-256 encryption and SHA-1 for integrity, which are both supported in an IPsec transform-set. However, the exhibit shows that the local peer is configured with Group 5 (Diffie-Hellman 1536-bit), while the remote peer likely expects a different DH group (e.g., Group 2 or Group 14). DH group mismatch during Phase 1 (IKE) negotiation causes the VPN tunnel to fail, even if encryption and integrity algorithms match.

What should I do if I get this SSCP question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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Last reviewed: Jun 30, 2026

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This SSCP 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 SSCP exam.