- A
Source NAT (SNAT)
Why wrong: SNAT translates the source IP address of outgoing packets, not the destination of incoming packets.
- B
Destination NAT (DNAT)
DNAT modifies the destination IP address of incoming packets, allowing them to be forwarded to an internal server.
- C
Static NAT
Why wrong: Static NAT provides a one-to-one mapping between a public and private IP address, but it is not specifically for translating the destination of inbound traffic; it translates both source and destination.
- D
Port Address Translation (PAT)
Why wrong: PAT is a form of SNAT that uses port numbers to map multiple private IPs to a single public IP; it is used for outbound traffic, not inbound destination translation.
Question 287 of 520
N10-009 Network Security Practice Question
This N10-009 practice question tests your understanding of network security. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 security analyst is configuring a firewall to allow HTTPS traffic from the internet to an internal web server with a private IP address. The firewall must translate the destination IP address of incoming packets to the private server IP. Which type of NAT should be configured?
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
✓
Destination NAT (DNAT)
Destination NAT (DNAT) is used to translate the destination IP address of incoming packets from a public IP to a private IP, allowing external HTTPS traffic to reach an internal web server. This is exactly what the scenario requires: the firewall must rewrite the destination address of packets arriving from the internet to the private server IP. DNAT is commonly implemented using the 'ip nat inside source static' command in Cisco IOS, where the 'inside' keyword refers to the translation of destination addresses for inbound traffic.
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.
- ✗
Source NAT (SNAT)
Why it's wrong here
SNAT translates the source IP address of outgoing packets, not the destination of incoming packets.
When this WOULD be correct
SNAT is correct when a firewall must translate the private source IP of internal hosts to a public IP for outbound internet access, such as allowing internal users to browse the web using a single public IP.
- ✓
Destination NAT (DNAT)
Why this is correct
DNAT modifies the destination IP address of incoming packets, allowing them to be forwarded to an internal server.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Static NAT
Why it's wrong here
Static NAT provides a one-to-one mapping between a public and private IP address, but it is not specifically for translating the destination of inbound traffic; it translates both source and destination.
When this WOULD be correct
Static NAT would be correct when a specific internal server (e.g., a mail server) must always be reachable from the internet using a fixed public IP address, and the mapping does not change over time. For example, a question stating 'A company needs to map a public IP to an internal server's private IP permanently for inbound traffic' would make Static NAT the answer.
- ✗
Port Address Translation (PAT)
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.
✓Destination NAT (DNAT)Correct answer▾
Why this is correct
DNAT modifies the destination IP address of incoming packets, allowing them to be forwarded to an internal server.
✗Source NAT (SNAT)Wrong answer — click to see why▾
Why this is wrong here
Source NAT (SNAT) changes the source IP address of outgoing packets, not the destination IP of incoming packets. This question requires translating the destination IP of incoming HTTPS traffic to the private server IP, which is DNAT.
★ When this WOULD be the correct answer
SNAT is correct when a firewall must translate the private source IP of internal hosts to a public IP for outbound internet access, such as allowing internal users to browse the web using a single public IP.
Why candidates choose this
Candidates may confuse SNAT with DNAT because both involve IP translation, or they might think 'source' refers to the traffic's origin (internet) rather than the packet's source address.
✗Static NATWrong answer — click to see why▾
Why this is wrong here
Static NAT maps a single public IP to a single private IP on a one-to-one basis, but the question specifies translating the destination IP of incoming HTTPS traffic to the private server IP, which is exactly what DNAT does. Static NAT is a type of DNAT, but the question asks for the type of NAT, and DNAT is the broader correct category.
★ When this WOULD be the correct answer
Static NAT would be correct when a specific internal server (e.g., a mail server) must always be reachable from the internet using a fixed public IP address, and the mapping does not change over time. For example, a question stating 'A company needs to map a public IP to an internal server's private IP permanently for inbound traffic' would make Static NAT the answer.
Why candidates choose this
Candidates may confuse Static NAT with DNAT because both involve destination translation, but Static NAT is a specific implementation. They might think 'static' implies a fixed mapping for inbound traffic, overlooking that DNAT is the general term for destination translation.
✗Port Address Translation (PAT)Wrong answer — click to see why▾
Why this is wrong here
PAT (Port Address Translation) translates multiple private IP addresses to a single public IP using different ports, but does not change the destination IP of incoming packets to reach an internal server. For HTTPS traffic from the internet to an internal server, DNAT is required to translate the destination IP.
★ When this WOULD be the correct answer
PAT would be correct when a firewall needs to allow multiple internal hosts to share a single public IP address for outbound internet access, translating source IPs and ports of outgoing packets.
Why candidates choose this
Candidates may confuse PAT with DNAT because both involve address translation, and PAT is commonly used for internet access, leading them to think it applies to inbound traffic as well.
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?”
Common exam traps
Common exam trap: answer the scenario, not the keyword
CompTIA often tests the distinction between SNAT and DNAT by describing a scenario where traffic comes from the internet to an internal server, and candidates mistakenly choose SNAT because they think 'source' refers to the packet's origin (the internet), when in fact SNAT always translates the source address of outbound traffic, not the destination of inbound traffic.
Detailed technical explanation
How to think about this question
Under the hood, DNAT works by modifying the destination IP address in the IP header of incoming packets as they traverse the firewall, typically using a NAT table entry that maps a public IP (and optionally a port) to a private IP. In Cisco IOS, this is configured with 'ip nat inside source static tcp <public-ip> <port> <private-ip> <port> extendable', which creates a static DNAT rule. A subtle behavior is that DNAT often requires a corresponding route on the firewall to ensure return traffic is un-translated correctly, and it is commonly used with 'ip nat outside' and 'ip nat inside' interface designations to control which direction the translation applies.
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
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FAQ
Questions learners often ask
What does this N10-009 question test?
Network Security — This question tests Network Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Destination NAT (DNAT) — Destination NAT (DNAT) is used to translate the destination IP address of incoming packets from a public IP to a private IP, allowing external HTTPS traffic to reach an internal web server. This is exactly what the scenario requires: the firewall must rewrite the destination address of packets arriving from the internet to the private server IP. DNAT is commonly implemented using the 'ip nat inside source static' command in Cisco IOS, where the 'inside' keyword refers to the translation of destination addresses for inbound traffic.
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.
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 →
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Last reviewed: Jun 30, 2026
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