The answer is that NAT is not configured, which is the most likely cause of the ASA firewall having no internet access for the specific VLAN. Even with a default route and a permissive ACL allowing all traffic from inside to outside, the Cisco ASA will drop packets from private IP addresses attempting to reach the public internet because it lacks a translation rule to convert those addresses into a routable public IP. Without NAT, the ASA cannot properly handle return traffic, as the private source addresses are not reachable across the internet. On the Cisco SCOR / CCNP Security Core 350-701 exam, this scenario tests your understanding of the ASA’s implicit requirement for NAT when traffic traverses from a higher-security to a lower-security interface—a common trap where candidates assume an ACL alone is sufficient. Remember the memory tip: “ACL permits, but NAT permits the return.”
350-701 Security Concepts Practice Question
This 350-701 practice question tests your understanding of security concepts. 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 issue where users on a specific VLAN cannot access the internet through a Cisco ASA firewall. The ASA has a default route pointing to the ISP router. The security policy includes an ACL that permits all traffic from the inside interface to the outside interface. What is the most likely cause of the problem?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
NAT (Network Address Translation) is not configured
The most likely cause is that NAT is not configured. Even though the ACL permits all traffic from inside to outside, the Cisco ASA requires NAT (or a NAT exemption rule) to translate private IP addresses to a routable public IP address when traffic traverses from a higher-security interface (inside) to a lower-security interface (outside). Without NAT, the ASA will drop the packets because it cannot determine how to route the private source addresses on the public internet, and the return traffic would have no way to reach the internal hosts.
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.
✗
The default route is misconfigured
Why it's wrong here
The default route exists and points to the ISP router.
✗
DNS is not resolving domain names
Why it's wrong here
DNS failure would affect name resolution but not basic IP connectivity.
✓
NAT (Network Address Translation) is not configured
Why this is correct
Without NAT, private IP addresses cannot reach the internet because they are not routable.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The ACL is blocking the traffic
Why it's wrong here
The ACL permits all traffic, so it is not blocking.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that an ACL permitting all traffic is sufficient for internet access, but the trap here is that the ASA requires NAT (or a NAT exemption) for traffic to traverse security levels, even when the ACL is permissive.
Detailed technical explanation
How to think about this question
On a Cisco ASA, NAT is implicitly required for traffic going from a higher-security interface (inside) to a lower-security interface (outside) unless a nat 0 or nat exempt rule is explicitly configured. The ASA uses NAT to translate the source IP address of internal hosts (e.g., 192.168.1.0/24) to the outside interface's public IP address, enabling return traffic to be routed back correctly. Without this translation, the ISP router would not know how to route return packets to the private IP addresses, and the ASA would drop the outbound packets due to the lack of a NAT rule in the global policy.
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 help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.
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.
Security Concepts — This question tests Security Concepts — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: NAT (Network Address Translation) is not configured — The most likely cause is that NAT is not configured. Even though the ACL permits all traffic from inside to outside, the Cisco ASA requires NAT (or a NAT exemption rule) to translate private IP addresses to a routable public IP address when traffic traverses from a higher-security interface (inside) to a lower-security interface (outside). Without NAT, the ASA will drop the packets because it cannot determine how to route the private source addresses on the public internet, and the return traffic would have no way to reach the internal hosts.
What should I do if I get this 350-701 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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 350-701 practice question is part of Courseiva's free Cisco 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 350-701 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.