- A
Static NAT
Why wrong: Static NAT maps a single private IP address to a single public IP address on a one-to-one basis, which does not allow sharing of one public address among many hosts.
- B
Dynamic NAT
Why wrong: Dynamic NAT uses a pool of public IP addresses, mapping private addresses on a first-come, first-served basis. It still requires multiple public addresses to serve multiple hosts.
- C
PAT (Port Address Translation)
PAT uses ports to differentiate between sessions from different hosts, allowing a single public IP address to serve many internal devices simultaneously.
- D
IP masquerading
Why wrong: While 'IP masquerading' is often used synonymously with PAT in Linux, it is not the formal industry term; PAT is the correct technical designation. But more importantly, the question is asking for the technique, and PAT is the standard answer in CompTIA objectives.
Quick Answer
The answer is PAT, or Port Address Translation, also known as NAT overload, because it is the only NAT technique that allows multiple internal hosts to share a single public IPv4 address. It accomplishes this by mapping each unique internal IP address and port number combination to a different source port on the public address, effectively creating many-to-one translation. On the CompTIA Network+ N10-009 exam, this concept tests your understanding of how small offices conserve scarce public IPs, and it often appears in scenario-based questions where the ISP provides only one address. A common trap is confusing static NAT or dynamic NAT, which are one-to-one mappings and would require multiple public IPs. Remember the memory tip: PAT = Port Address Translation, and think of it as “port overload” because it overloads a single IP by using thousands of unique port numbers to keep each session separate.
N10-009 Network Implementation Practice Question
This N10-009 practice question tests your understanding of network implementation. Compare every option against the stated constraints before choosing — the best answer satisfies all requirements, not just the most obvious one. 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 small office has multiple devices that need internet access but the ISP provides only a single public IPv4 address. Which network address translation (NAT) technique is most appropriate to allow all internal hosts to share that one public address?
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
PAT (Port Address Translation)
PAT (Port Address Translation), also known as NAT overload, is the correct choice because it allows multiple internal hosts to share a single public IPv4 address by mapping each unique internal IP:port combination to a different source port on the public address. This is the only NAT technique that provides many-to-one address translation, which is exactly what a small office with more devices than public IPs requires.
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.
- ✗
Static NAT
Why it's wrong here
Static NAT maps a single private IP address to a single public IP address on a one-to-one basis, which does not allow sharing of one public address among many hosts.
- ✗
Dynamic NAT
Why it's wrong here
Dynamic NAT uses a pool of public IP addresses, mapping private addresses on a first-come, first-served basis. It still requires multiple public addresses to serve multiple hosts.
- ✓
PAT (Port Address Translation)
Why this is correct
PAT uses ports to differentiate between sessions from different hosts, allowing a single public IP address to serve many internal devices simultaneously.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
IP masquerading
Why it's wrong here
While 'IP masquerading' is often used synonymously with PAT in Linux, it is not the formal industry term; PAT is the correct technical designation. But more importantly, the question is asking for the technique, and PAT is the standard answer in CompTIA objectives.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between Dynamic NAT and PAT by presenting a scenario with a single public IP, where candidates mistakenly choose Dynamic NAT because they confuse 'dynamic' with 'shared,' not realizing Dynamic NAT still requires a pool of public IPs.
Detailed technical explanation
How to think about this question
PAT works by modifying the source port number in the TCP/UDP header to a unique value for each session, while keeping the single public IP address constant; the NAT device maintains a translation table that tracks these port mappings. A subtle behavior is that PAT can exhaust available port numbers (over 65,000 per IP) under extreme load, and it may fail for protocols like IPsec or FTP that embed IP addresses in the payload unless ALG (Application Layer Gateway) support is enabled. In real-world scenarios, PAT is the default configuration on most home and small office routers because it conserves IPv4 addresses efficiently.
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.
What to study next
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FAQ
Questions learners often ask
What does this N10-009 question test?
Network Implementation — This question tests Network Implementation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: PAT (Port Address Translation) — PAT (Port Address Translation), also known as NAT overload, is the correct choice because it allows multiple internal hosts to share a single public IPv4 address by mapping each unique internal IP:port combination to a different source port on the public address. This is the only NAT technique that provides many-to-one address translation, which is exactly what a small office with more devices than public IPs requires.
What should I do if I get this N10-009 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.
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Last reviewed: Jun 11, 2026
This N10-009 practice question is part of Courseiva's free CompTIA 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 N10-009 exam.
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