The answer is to check the crypto map configuration on the Cisco ASA and ensure it matches the peer IP and proxy IDs. This is correct because the ASA log message “no matching crypto map entry for traffic” directly indicates a mismatch between the crypto map’s defined interesting traffic (proxy IDs) or peer address and the actual traffic flow, even when IKEv2 proposals match. On the CompTIA SecurityX CAS-004 exam, this scenario tests your ability to troubleshoot IPsec VPN connectivity in hybrid cloud architectures, a common trap being that engineers focus on IKE phase 1 policies when the real issue lies in phase 2 crypto map definitions. Remember that a crypto map binds the peer, the transform set, and the ACL defining which traffic to encrypt—if any of these are misaligned, the ASA will drop or send traffic in the clear, risking data leakage. A useful memory tip is “peer, proxy, policy”—always verify the crypto map’s peer IP and proxy IDs match the remote gateway and subnets before adjusting anything else.
CAS-004 Security Engineering Practice Question
This CAS-004 practice question tests your understanding of security engineering. 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 financial company is expanding its hybrid cloud architecture. They have an AWS VPC connected to an on-premises network via an IPsec VPN using IKEv2. The on-premises firewall is a Cisco ASA. Recently, users report intermittent connectivity to cloud resources. The security team reviews logs and finds the following message on the ASA: 'no matching crypto map entry for traffic from on-prem to cloud'. The team also suspects potential data leakage due to occasional unencrypted traffic. The corporate policy requires all traffic between environments to be encrypted. The engineer has verified that the IKEv2 proposals match on both sides. The cloud side uses a virtual private gateway with a static route to the on-premises network. Which of the following should the engineer do FIRST to resolve the issue?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Check the crypto map configuration on the Cisco ASA and ensure it matches the peer IP and proxy IDs
Option B is correct because the error message directly indicates a crypto map mismatch. Checking and adjusting the crypto map on the ASA to match the peer IP and proxy IDs will resolve the issue. Option A is incorrect because IKEv2 policies already match. Option C is too drastic and not the first step. Option D could actually cause connectivity issues if NAT traversal is required.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Check the crypto map configuration on the Cisco ASA and ensure it matches the peer IP and proxy IDs
Why this is correct
The 'no matching crypto map entry' error is resolved by correcting the crypto map.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
✗
Disable NAT traversal on both VPN endpoints
Why it's wrong here
NAT traversal is often required for VPNs behind NAT; disabling it may cause further issues.
✗
Reconfigure the IKEv2 policies on both sides to use different encryption algorithms
Why it's wrong here
The problem is not IKEv2 policy mismatch; the error points to crypto map.
✗
Replace the VPN connection with AWS Direct Connect for dedicated bandwidth
Why it's wrong here
This is an expensive and unnecessary escalation; the issue is configuration, not connectivity type.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Got this wrong? Here's your next step.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related CAS-004 NAT questions on configuration and troubleshooting.
Security Engineering — This question tests Security Engineering — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Check the crypto map configuration on the Cisco ASA and ensure it matches the peer IP and proxy IDs — Option B is correct because the error message directly indicates a crypto map mismatch. Checking and adjusting the crypto map on the ASA to match the peer IP and proxy IDs will resolve the issue. Option A is incorrect because IKEv2 policies already match. Option C is too drastic and not the first step. Option D could actually cause connectivity issues if NAT traversal is required.
What should I do if I get this CAS-004 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related CAS-004 NAT questions on configuration and troubleshooting.
Are there clue words in this question I should notice?
Yes — watch for: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This CAS-004 practice question is part of Courseiva's free CompTIA 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 CAS-004 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.