Question 470 of 2,152

NAT and PAT →mediumMultiple ChoiceObjective-mapped

300-410 NAT and PAT Practice Question

This 300-410 practice question tests your understanding of nat and pat. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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.

An engineer configures NAT on a router with 'ip nat inside source list 1 pool POOL overload' where POOL contains 203.0.113.1-203.0.113.5. The inside hosts are 10.0.0.0/24. Traffic works, but the engineer notices that some hosts are assigned the same public IP and port, causing conflicts. 'Show ip nat translations' shows entries with the same inside global IP and port for different inside local hosts. What is the most likely cause?

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.

A
The pool has only one IP address, and the router is reusing ports for different hosts.
Why wrong: Incorrect because PAT should assign different ports even with one IP; reusing the same port for different hosts would cause conflicts and is not normal behavior.
B
The 'ip nat inside source' command is missing the 'overload' keyword.
Why wrong: Incorrect because 'overload' is configured; the issue is not about missing overload.
C
The router is not performing PAT correctly because the ACL permits more than the pool can handle.
Why wrong: Incorrect because PAT should still assign unique ports; the issue is likely a bug or misconfiguration.
D
The router has a configuration that uses 'ip nat inside source static' for some hosts, conflicting with the dynamic pool.
Correct because if a static NAT entry maps a host to the same public IP as the pool, and the static entry does not use port translation, it can cause conflicts with dynamic entries.

Full breakdown with real-world context →

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

✓

The router has a configuration that uses 'ip nat inside source static' for some hosts, conflicting with the dynamic pool.

Option D is correct because the scenario describes a PAT overload configuration where the pool has five IP addresses (203.0.113.1–203.0.113.5). If static NAT entries are also configured for some hosts, those static mappings reserve specific inside global IPs and ports, forcing the dynamic PAT process to reuse the same global IP and port for multiple inside local hosts when it runs out of unique combinations. This conflict causes the observed duplicate inside global IP and port entries in the translation table.

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 pool has only one IP address, and the router is reusing ports for different hosts.
Why it's wrong here
Incorrect because PAT should assign different ports even with one IP; reusing the same port for different hosts would cause conflicts and is not normal behavior.
✗
The 'ip nat inside source' command is missing the 'overload' keyword.
Why it's wrong here
Incorrect because 'overload' is configured; the issue is not about missing overload.
✗
The router is not performing PAT correctly because the ACL permits more than the pool can handle.
Why it's wrong here
Incorrect because PAT should still assign unique ports; the issue is likely a bug or misconfiguration.
✓
The router has a configuration that uses 'ip nat inside source static' for some hosts, conflicting with the dynamic pool.
Why this is correct
Correct because if a static NAT entry maps a host to the same public IP as the pool, and the static entry does not use port translation, it can cause conflicts with dynamic entries.
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.

Common exam traps

Common exam trap: answer the scenario, not the keyword

Cisco often tests the interaction between static NAT and dynamic PAT, where candidates mistakenly attribute the duplicate translation entries to PAT misconfiguration or pool exhaustion rather than recognizing that static entries consume resources and force reuse.

Detailed technical explanation

How to think about this question

When 'ip nat inside source static' is used, it creates a permanent 1:1 mapping that reserves a specific inside global IP and often a fixed port (e.g., for TCP/UDP). The dynamic PAT process, governed by RFC 2663, must avoid using those reserved resources; if the pool is small or static entries occupy many ports, the dynamic allocator may be forced to reuse the same global IP and port for different inside hosts, violating the uniqueness requirement of PAT. In real-world deployments, mixing static and dynamic NAT on the same pool is a common misconfiguration that leads to translation collisions and connectivity issues.

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.

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.

10 questions 20 questions 30 questions 50 questions Timed 30

300-410 practice-test guide →Study guide →Browse all practice tests

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: The router has a configuration that uses 'ip nat inside source static' for some hosts, conflicting with the dynamic pool. — Option D is correct because the scenario describes a PAT overload configuration where the pool has five IP addresses (203.0.113.1–203.0.113.5). If static NAT entries are also configured for some hosts, those static mappings reserve specific inside global IPs and ports, forcing the dynamic PAT process to reuse the same global IP and port for multiple inside local hosts when it runs out of unique combinations. This conflict causes the observed duplicate inside global IP and port entries in the translation table.

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.

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 →

How Courseiva writes practice questions · Editorial policy

Keep practising

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.

Loading comments…

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.