N10-009 Network Implementation Practice Question
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?
⚠ Common exam trap
The N10-009 exam 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.
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.
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 establishes a permanent, one-to-one mapping between a specific private IP address and a specific public IP address. This configuration is primarily used for servers or devices that require consistent inbound access from the internet, as the public IP remains constant. It is unsuitable for a scenario where multiple internal devices need to share a single public IP for outbound internet access, as each device would require its own dedicated public IP.
When this WOULD be correct
A question where an internal server (e.g., a web server) must be accessible from the internet using a fixed public IP address, and the internal host's private IP must remain constant.
- ✗
Dynamic NAT
Why it's wrong here
Dynamic NAT allocates a public IP address from a predefined pool to an internal device on a temporary, first-come, first-served basis. While it allows multiple internal devices to access the internet, each active session still consumes a distinct public IP address from the pool. This method is inefficient and costly for a small office aiming to provide internet access to many devices using a limited number of public IP addresses, as it doesn't allow true sharing of a *single* public IP.
- ✓
PAT (Port Address Translation)
Why this is correct
PAT, also known as NAT Overload, is the most common form of NAT used in small offices and homes. It allows multiple internal devices to share a single public IP address by translating both the source IP address and the source port number of outbound connections. The router maintains a translation table, mapping unique internal IP:port combinations to the single public IP with a unique public port, enabling simultaneous internet access for many hosts.
- ✗
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.
When this WOULD be correct
In a scenario where the question specifically asks about Linux iptables or router configuration using the term 'masquerade' (e.g., 'Which NAT technique is implemented using the MASQUERADE target in iptables?'), IP masquerading would be the correct answer.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The N10-009 exam frequently reuses these exact scenarios with slightly different constraints.
✓PAT (Port Address Translation)Correct answer▾
Why this is correct
PAT, also known as NAT Overload, is the most common form of NAT used in small offices and homes. It allows multiple internal devices to share a single public IP address by translating both the source IP address and the source port number of outbound connections. The router maintains a translation table, mapping unique internal IP:port combinations to the single public IP with a unique public port, enabling simultaneous internet access for many hosts.
✗Static NATWrong answer — click to see why▾
Why this is wrong here
Static NAT maps a single public IP to a single private IP one-to-one, so it cannot allow multiple internal hosts to share one public address.
★ When this WOULD be the correct answer
A question where an internal server (e.g., a web server) must be accessible from the internet using a fixed public IP address, and the internal host's private IP must remain constant.
Why candidates choose this
Candidates may confuse static NAT with PAT because both involve address translation, but static NAT lacks port multiplexing needed for sharing a single IP among many hosts.
✗IP masqueradingWrong answer — click to see why▾
Why this is wrong here
IP masquerading is a term often used interchangeably with PAT in Linux, but in the context of this CompTIA question, PAT is the standard term. The question asks for the 'most appropriate' technique, and PAT is the correct answer; IP masquerading is not a distinct technique recognized in the CompTIA objectives.
★ When this WOULD be the correct answer
In a scenario where the question specifically asks about Linux iptables or router configuration using the term 'masquerade' (e.g., 'Which NAT technique is implemented using the MASQUERADE target in iptables?'), IP masquerading would be the correct answer.
Why candidates choose this
Candidates may have encountered the term 'IP masquerading' in Linux networking contexts and mistakenly believe it is a separate NAT technique, or they may confuse it with PAT due to similar functionality.
Analysis generated from the official N10-009blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Visual reference
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Related to this question
Learn chapter
Physical Network Infrastructure
Key term
ISP
An ISP is a company that provides individuals and organizations access to the Internet, along with related services like email and web hosting.
Key term
NAT overload
NAT overload is a form of network address translation that allows many devices on a private network to share a single public IP address by using unique port numbers to track each connection.
About these practice questions
One of 464 original N10-009 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.