- 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.
Symptoms of NAT Misconfiguration
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.)
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.”
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.
Option A is correct because if inside hosts can ping the outside interface IP but cannot reach hosts beyond it, this indicates that NAT is translating the source address correctly for outbound traffic, but the router is not performing NAT for destinations beyond the outside interface. This typically happens when the NAT configuration lacks an access list that matches the inside-to-outside traffic or when the ip nat inside/outside interface commands are misapplied, causing the router to forward packets without translation for destinations beyond the directly connected network.
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.
- ✓
Inside hosts can ping the outside interface IP but cannot reach hosts beyond it.
Why this is correct
This often indicates that NAT is not translating the source address for packets going out, or the return traffic is not being untranslated.
Related concept
Read the scenario before looking for a memorised answer.
- ✓
Traffic flows in one direction only (e.g., inside-to-outside works, but return traffic fails).
Why this is correct
Asymmetric routing or missing NAT entries can cause one-way traffic; the router may not have a translation for the return packet.
Related concept
Read the scenario before looking for a memorised answer.
- ✓
The show ip nat translations output shows many translations with the same inside global address but different ports, and new connections fail.
Why this is correct
This indicates PAT port exhaustion; when all available ports are used, new translations cannot be created.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
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: answer the scenario, not the keyword
Cisco often tests the distinction between connectivity to the outside interface (which does not require NAT) and connectivity beyond it (which requires proper NAT translation), leading candidates to mistakenly think that successful pings to the outside interface imply full NAT functionality.
Detailed technical explanation
How to think about this question
NAT uses the ip nat inside source list command to define which traffic to translate, and the ip nat inside/outside interface commands to mark translation boundaries. When inside hosts can reach the outside interface IP, it confirms that the inside interface is correctly configured and that basic IP connectivity exists, but failure to reach beyond indicates that the NAT translation is not being applied to packets destined for non-local subnets, often due to missing or incorrect ACL entries or misordered NAT rules. In real-world scenarios, this symptom is common when a static NAT or dynamic NAT pool is exhausted or when the ACL does not include the destination networks.
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 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.
Visual reference
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.
- →
NAT and PAT — study guide chapter
Learn the concepts, then practise the questions
- →
NAT and PAT practice questions
Targeted practice on this topic area only
- →
All 300-410 questions
2,152 questions across all exam domains
- →
Cisco CCNP ENARSI 300-410 study guide
Full concept coverage aligned to exam objectives
- →
300-410 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Related 300-410 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Layer 3 Technologies practice questions
Practise 300-410 questions linked to Layer 3 Technologies.
EIGRP Troubleshooting practice questions
Practise 300-410 questions linked to EIGRP Troubleshooting.
OSPF Troubleshooting (v2/v3) practice questions
Practise 300-410 questions linked to OSPF Troubleshooting (v2/v3).
BGP Troubleshooting practice questions
Practise 300-410 questions linked to BGP Troubleshooting.
Route Redistribution practice questions
Practise 300-410 questions linked to Route Redistribution.
Policy-Based Routing (PBR) practice questions
Practise 300-410 questions linked to Policy-Based Routing (PBR).
VRF-Lite practice questions
Practise 300-410 questions linked to VRF-Lite.
Route Maps and Route Filtering practice questions
Practise 300-410 questions linked to Route Maps and Route Filtering.
Administrative Distance practice questions
Practise 300-410 questions linked to Administrative Distance.
Route Summarization practice questions
Practise 300-410 questions linked to Route Summarization.
Bidirectional Forwarding Detection (BFD) practice questions
Practise 300-410 questions linked to Bidirectional Forwarding Detection (BFD).
VPN Technologies practice questions
Practise 300-410 questions linked to VPN Technologies.
Practice this exam
Start a free 300-410 practice session
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Questions learners often ask
What does this 300-410 question test?
NAT and PAT — This question tests NAT and PAT — Read the scenario before looking for a memorised answer..
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. — Option A is correct because if inside hosts can ping the outside interface IP but cannot reach hosts beyond it, this indicates that NAT is translating the source address correctly for outbound traffic, but the router is not performing NAT for destinations beyond the outside interface. This typically happens when the NAT configuration lacks an access list that matches the inside-to-outside traffic or when the ip nat inside/outside interface commands are misapplied, causing the router to forward packets without translation for destinations beyond the directly connected network.
What should I do if I get this 300-410 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
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 →
Keep practising
More 300-410 practice questions
- Drag and drop the steps to negotiate an IKEv2 IPsec site-to-site tunnel into the correct order, from first to last.
- Drag and drop the steps to troubleshoot an IPsec site-to-site VPN adjacency failure into the correct order, from first t…
- Drag and drop the steps to verify and validate the operational state of an IPsec site-to-site VPN into the correct order…
- Consider the following configuration snippet: ip cef ! interface GigabitEthernet0/0 ip address 10.0.0.1 255.255.255.25…
- A router is configured with 'logging host 10.1.1.100' and 'logging trap informational'. The engineer notices that syslog…
- Drag and drop the steps to configure a GRE tunnel for IPv6 over IPv4 into the correct order, from first to last.
Last reviewed: Jul 4, 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.
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.