- A
Inside hosts can ping the outside interface IP but cannot reach hosts beyond it.
This often indicates that NAT is not translating the source address for packets going out, or the return traffic is not being untranslated.
- B
Traffic flows in one direction only (e.g., inside-to-outside works, but return traffic fails).
Asymmetric routing or missing NAT entries can cause one-way traffic; the router may not have a translation for the return packet.
- C
The show ip nat translations output shows many translations with the same inside global address but different ports, and new connections fail.
This indicates PAT port exhaustion; when all available ports are used, new translations cannot be created.
- D
The router's CPU utilization is high due to BGP process.
Why wrong: High CPU from BGP is unrelated to NAT; NAT issues typically do not cause high CPU unless there is a bug or extremely high traffic.
- E
The show ip route command shows a default route pointing to the ISP next hop.
Why wrong: A default route is normal for internet access and does not indicate a NAT problem.
Quick Answer
The answer is that NAT misconfiguration or failure is indicated by an inability to ping from inside to outside due to no translation, asymmetric routing causing one-way traffic, and translation table exhaustion where new connections fail. These symptoms arise because NAT relies on a consistent mapping between private and public addresses; when the translation table is full or routing paths are mismatched, packets cannot be properly translated or returned, breaking connectivity. On the Cisco CCNP ENARSI 300-410 exam, this topic tests your ability to diagnose NAT issues in complex enterprise networks, often appearing in scenario-based multiple-choice questions where you must distinguish true NAT failures from unrelated problems like ACL misconfigurations or routing protocol errors. A common trap is confusing port address translation (PAT) overload with a true failure—many translations sharing one inside global address with different ports is normal PAT behavior, not a symptom of misconfiguration. Remember the memory tip: “No ping, one-way, or full table—NAT is unstable.”
300-410 NAT and PAT Practice Question
This 300-410 practice question tests your understanding of nat and pat. 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.
Which THREE symptoms indicate that NAT is misconfigured or failing on a Cisco router? (Choose THREE.)
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
Inside hosts can ping the outside interface IP but cannot reach hosts beyond it.
Common NAT failure symptoms include: inability to ping from inside to outside (no translation), asymmetric routing causing one-way traffic, and translation table exhaustion. The other options describe unrelated issues.
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.
- ✓
Inside hosts can ping the outside interface IP but cannot reach hosts beyond it.
- ✓
Traffic flows in one direction only (e.g., inside-to-outside works, but return traffic fails).
- ✓
The show ip nat translations output shows many translations with the same inside global address but different ports, and new connections fail.
- ✗
The router's CPU utilization is high due to BGP process.
- ✗
The show ip route command shows a default route pointing to the ISP next hop.
Why it's wrong here
A default route is normal for internet access and does not indicate a NAT problem.
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 300-410 NAT questions on configuration and troubleshooting.
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NAT and PAT — study guide chapter
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NAT and PAT practice questions
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FAQ
Questions learners often ask
What does this 300-410 question test?
NAT and PAT — This question tests NAT and PAT — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Inside hosts can ping the outside interface IP but cannot reach hosts beyond it. — Common NAT failure symptoms include: inability to ping from inside to outside (no translation), asymmetric routing causing one-way traffic, and translation table exhaustion. The other options describe unrelated issues.
What should I do if I get this 300-410 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 300-410 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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Last reviewed: Jun 19, 2026
This 300-410 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 300-410 exam.
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