- A
The access list 100 does not permit the 172.16.0.0/16 network.
Correct because the NAT configuration only translates traffic that matches the access list; hosts not in the list are not translated.
- B
The router's interface GigabitEthernet0/0 is not configured with ip nat outside.
Why wrong: Incorrect because if the outside interface were missing the command, no translations would work at all.
- C
The 172.16.0.0/16 hosts have a default gateway pointing to a different router.
Why wrong: Incorrect because the engineer verified connectivity to the router, implying the default gateway is correct.
- D
The NAT pool is exhausted for the 172.16.0.0/16 network.
Why wrong: Incorrect because the configuration uses overload (PAT), which does not require a pool; it uses the interface IP.
Quick Answer
The answer is that the access list 100 does not permit the 172.16.0.0/16 network. This is correct because the NAT access list permit network command defines exactly which inside local addresses are eligible for translation; if an address is not matched by the permit statement, the router will not create a NAT entry for it, and traffic from that host will be forwarded without translation, failing to reach the internet. On the ENCOR 350-401 exam, this scenario tests your understanding that the access list acts as a gatekeeper for NAT—a common trap is assuming that any internal host with connectivity to the router will automatically be translated. Remember, the access list must explicitly permit each network you intend to translate. A useful memory tip: “If it’s not in the list, it doesn’t get kissed”—meaning no permit, no translation.
350-401 NAT and DHCP Practice Question
This 350-401 practice question tests your understanding of nat and dhcp. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 configuring NAT on a Cisco router to allow internal hosts to access the internet. The engineer uses the command ip nat inside source list 100 interface GigabitEthernet0/0 overload, where access list 100 permits only the 10.0.0.0/8 network. After testing, hosts in the 10.0.0.0/8 network can access the internet, but hosts in the 172.16.0.0/16 network cannot. The engineer verifies that the 172.16.0.0/16 hosts have connectivity to the router. 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.
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 access list 100 does not permit the 172.16.0.0/16 network.
The access list used in the NAT command determines which inside local addresses are eligible for translation. If the access list does not include the 172.16.0.0/16 network, those hosts will not be translated and will not be able to reach the internet.
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.
- ✓
The access list 100 does not permit the 172.16.0.0/16 network.
Why this is correct
Correct because the NAT configuration only translates traffic that matches the access list; hosts not in the list are not translated.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
- ✗
The router's interface GigabitEthernet0/0 is not configured with ip nat outside.
Why it's wrong here
Incorrect because if the outside interface were missing the command, no translations would work at all.
- ✗
The 172.16.0.0/16 hosts have a default gateway pointing to a different router.
Why it's wrong here
Incorrect because the engineer verified connectivity to the router, implying the default gateway is correct.
- ✗
The NAT pool is exhausted for the 172.16.0.0/16 network.
Why it's wrong here
Incorrect because the configuration uses overload (PAT), which does not require a pool; it uses the interface IP.
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.
Trap categories for this question
Command / output trap
Incorrect because if the outside interface were missing the command, no translations would work at all.
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 350-401 NAT questions on configuration and troubleshooting.
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FAQ
Questions learners often ask
What does this 350-401 question test?
NAT and DHCP — This question tests NAT and DHCP — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The access list 100 does not permit the 172.16.0.0/16 network. — The access list used in the NAT command determines which inside local addresses are eligible for translation. If the access list does not include the 172.16.0.0/16 network, those hosts will not be translated and will not be able to reach the internet.
What should I do if I get this 350-401 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 350-401 NAT questions on configuration and troubleshooting.
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?
Static NAT maps one inside address to one outside address.
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Last reviewed: Jun 18, 2026
This 350-401 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 350-401 exam.
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