This SSCP practice question tests your understanding of sscp exam topics. 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?
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
A
Transform-set
Why wrong: The transform-set uses AES-256 and SHA-1, which matches the peer.
B
Pre-shared key
Why wrong: Pre-shared key is configured but not shown; mismatch would cause failure but is not indicated.
C
Group 5
Group 5 (DH5) is deprecated; the peer may require a stronger DH group.
D
IKE lifetime
Why wrong: Lifetime mismatch can cause renegotiation issues but is not the most likely problem.
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.
Quick reference
VPN Protocol Comparison
Protocol
Port
Encryption
Authentication
Use Case
IKEv2 / IPsec
UDP 500 / 4500
AES-256
Certificates / PSK
Site-to-site & remote access
SSL / TLS VPN
TCP 443
TLS 1.3
Certificates / MFA
Clientless remote access
L2TP / IPsec
UDP 1701
AES (IPsec)
PSK / Certificates
Legacy remote access
WireGuard
UDP 51820
ChaCha20
Public keys
Modern high-performance VPN
PPTP
TCP 1723
MPPE (weak)
MS-CHAPv2
Legacy — avoid in production
PPTP is considered insecure. IKEv2/IPsec and SSL VPN are the current recommended options.
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.
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.
About these practice questions
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These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A network engineer is troubleshooting a site-to-site VPN that is failing to establish. The pre-shared key is correct and both sides use IKEv2. The VPN logs show 'no proposal chosen'. What is the most likely cause?
medium
A.Firewall blocking UDP port 500
B.Incorrect peer IP address
✓ C.Mismatched encryption algorithms
D.Expired certificates
Why C: The 'no proposal chosen' error in IKEv2 indicates that the two VPN peers cannot agree on a common set of security parameters during the IKE_SA_INIT exchange. Since the pre-shared key is correct and both sides use IKEv2, the most likely cause is a mismatch in the encryption algorithms (e.g., AES-256 vs. AES-128), hash algorithms (e.g., SHA-256 vs. SHA-1), or Diffie-Hellman groups (e.g., group 14 vs. group 2). This prevents the IKE security association from being established.
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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.
Question Discussion
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