- A
A) Port forwarding (DNAT) rule
Correct. Port forwarding translates the destination IP and port of incoming traffic from the public IP to the private IP of the web server, allowing external access.
- B
B) Allow rule with source any, destination 10.0.0.5, port 443
Why wrong: Incorrect. An allow rule alone does not change the destination IP. The incoming packet's destination is 203.0.113.10, not 10.0.0.5, so the server would not receive the traffic without address translation.
- C
C) Access control list on the internal interface
Why wrong: Incorrect. An ACL on the internal interface could be used to control traffic within the LAN, but it does not enable external traffic to reach the internal server.
- D
D) VPN rule to require remote access VPN
Why wrong: Incorrect. While a VPN would provide secure access, the scenario does not mention a VPN. The goal is to allow access directly via the internet without requiring a VPN.
Quick Answer
The correct answer is a port forwarding (DNAT) rule. This is required because the internal web server uses a private IP address (10.0.0.5) from the RFC 1918 range, which cannot be routed across the public internet. The firewall must perform destination network address translation (DNAT) to rewrite the destination of incoming traffic from its public IP (203.0.113.10) on port 443 to the server’s private address, effectively bridging the gap between the public and private networks. On the CompTIA Network+ N10-009 exam, this scenario tests your understanding of how firewalls enable internal server access from the internet without exposing the private IP directly. A common trap is confusing this with a standard ACL or static route—remember that port forwarding specifically changes the destination IP, not just the port. For a quick memory tip: think “DNAT = Destination NAT = Directs traffic to a private IP.”
N10-009 Network Security Practice Question
This N10-009 practice question tests your understanding of network security. 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 security administrator is configuring a firewall to allow remote employees to access the company's internal web server (port 443) from the internet. The web server has an internal IP address of 10.0.0.5. The firewall has a public IP of 203.0.113.10. Which type of firewall rule should be created?
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
A) Port forwarding (DNAT) rule
A port forwarding (DNAT) rule is required because the web server uses a private RFC 1918 IP address (10.0.0.5), which is not routable on the public internet. The firewall must translate the destination IP from its public address (203.0.113.10) to the internal server's private address, allowing inbound traffic on port 443 to reach the correct internal host.
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.
- ✓
A) Port forwarding (DNAT) rule
Why this is correct
Correct. Port forwarding translates the destination IP and port of incoming traffic from the public IP to the private IP of the web server, allowing external access.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
B) Allow rule with source any, destination 10.0.0.5, port 443
Why it's wrong here
Incorrect. An allow rule alone does not change the destination IP. The incoming packet's destination is 203.0.113.10, not 10.0.0.5, so the server would not receive the traffic without address translation.
- ✗
C) Access control list on the internal interface
Why it's wrong here
Incorrect. An ACL on the internal interface could be used to control traffic within the LAN, but it does not enable external traffic to reach the internal server.
- ✗
D) VPN rule to require remote access VPN
Why it's wrong here
Incorrect. While a VPN would provide secure access, the scenario does not mention a VPN. The goal is to allow access directly via the internet without requiring a VPN.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse a simple 'allow' rule with the necessary NAT translation, failing to realize that without DNAT, the firewall has no way to forward the packet to the private IP address of the internal server.
Trap categories for this question
Scenario analysis trap
Incorrect. While a VPN would provide secure access, the scenario does not mention a VPN. The goal is to allow access directly via the internet without requiring a VPN.
Detailed technical explanation
How to think about this question
Destination NAT (DNAT) rewrites the destination IP address and port of incoming packets at the firewall's external interface before the routing decision is made. In a typical implementation, the firewall maintains a NAT table that maps the public IP:port (203.0.113.10:443) to the private IP:port (10.0.0.5:443), and the return traffic undergoes reverse NAT automatically. A common real-world pitfall is forgetting to also create a corresponding allow rule in the firewall's security policy for the translated traffic, which can cause the connection to fail even with correct DNAT configuration.
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
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.
- →
Network Security — study guide chapter
Learn the concepts, then practise the questions
- →
Network Security practice questions
Targeted practice on this topic area only
- →
All N10-009 questions
520 questions across all exam domains
- →
CompTIA Network+ N10-009 study guide
Full concept coverage aligned to exam objectives
- →
N10-009 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Related N10-009 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Networking Concepts practice questions
Practise N10-009 questions linked to Networking Concepts.
Network Implementation practice questions
Practise N10-009 questions linked to Network Implementation.
Network Operations practice questions
Practise N10-009 questions linked to Network Operations.
Network Security practice questions
Practise N10-009 questions linked to Network Security.
Network Troubleshooting practice questions
Practise N10-009 questions linked to Network Troubleshooting.
Network+ network fundamentals practice questions
Practise N10-009 questions linked to Network+ network fundamentals.
Practice this exam
Start a free N10-009 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 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: A) Port forwarding (DNAT) rule — A port forwarding (DNAT) rule is required because the web server uses a private RFC 1918 IP address (10.0.0.5), which is not routable on the public internet. The firewall must translate the destination IP from its public address (203.0.113.10) to the internal server's private address, allowing inbound traffic on port 443 to reach the correct internal host.
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 →
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.
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.