- A
The interface GigabitEthernet0/1 has a private IP address; configure a public IP or use a NAT pool.
If the interface IP is private, NAT will use that private IP, causing the issue.
- B
The access-list 100 is incorrectly matching traffic.
Why wrong: The translation shows the correct inside local address, so ACL is working.
- C
The server is responding to the wrong IP due to asymmetric routing.
Why wrong: The server sees the source IP as 10.1.1.1, which is the translated address.
- D
The NAT configuration is missing the 'overload' keyword.
Why wrong: The configuration includes 'overload', and translations are occurring.
Question 1,927 of 2,152
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.
Router R1 is configured with ip nat inside source list 100 interface GigabitEthernet0/1 overload. Internal hosts can access the internet, but traffic to a specific external server at 203.0.113.100 is being translated to a different source IP than expected. Router R1 shows: show ip nat translations: Pro Inside global Inside local Outside local Outside global --- 10.1.1.1 192.168.1.1 203.0.113.100 203.0.113.100. The server logs show connections from 10.1.1.1 instead of 203.0.113.1. What is the root cause?
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 interface GigabitEthernet0/1 has a private IP address; configure a public IP or use a NAT pool.
The correct answer is A because the NAT configuration uses `ip nat inside source list 100 interface GigabitEthernet0/1 overload`, which translates inside local addresses to the IP address of the GigabitEthernet0/1 interface. If that interface has a private IP address (e.g., 10.1.1.1), then all translated traffic will appear to come from that private address, not a public one. The server logs confirm this by showing connections from 10.1.1.1 instead of a public IP like 203.0.113.1, indicating the interface lacks a public IP or a NAT pool with a routable address.
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 interface GigabitEthernet0/1 has a private IP address; configure a public IP or use a NAT pool.
Why this is correct
If the interface IP is private, NAT will use that private IP, causing the issue.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
The access-list 100 is incorrectly matching traffic.
Why it's wrong here
The translation shows the correct inside local address, so ACL is working.
- ✗
The server is responding to the wrong IP due to asymmetric routing.
Why it's wrong here
The server sees the source IP as 10.1.1.1, which is the translated address.
- ✗
The NAT configuration is missing the 'overload' keyword.
Why it's wrong here
The configuration includes 'overload', and translations are occurring.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that the `interface` keyword in `ip nat inside source list` automatically uses a public IP, but the trap is that it simply uses whatever IP is configured on that interface, which could be private if misconfigured.
Trap categories for this question
Command / output trap
The translation shows the correct inside local address, so ACL is working.
Detailed technical explanation
How to think about this question
When using `ip nat inside source list <acl> interface <interface> overload`, the router dynamically uses the primary IP address of the specified interface as the global address for PAT. If that interface has a private IP (e.g., 10.0.0.1 per RFC 1918), the translated packets will carry that private source IP, which is not routable on the public internet and will be dropped or logged as unexpected. In real-world scenarios, this often occurs when an engineer mistakenly configures NAT to the LAN-facing interface or forgets to assign a public IP to the WAN interface, leading to connectivity failures or incorrect source addresses in server logs.
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: The interface GigabitEthernet0/1 has a private IP address; configure a public IP or use a NAT pool. — The correct answer is A because the NAT configuration uses `ip nat inside source list 100 interface GigabitEthernet0/1 overload`, which translates inside local addresses to the IP address of the GigabitEthernet0/1 interface. If that interface has a private IP address (e.g., 10.1.1.1), then all translated traffic will appear to come from that private address, not a public one. The server logs confirm this by showing connections from 10.1.1.1 instead of a public IP like 203.0.113.1, indicating the interface lacks a public IP or a NAT pool with a routable address.
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.