The answer is a missing or misconfigured firewall policy for HTTPS traffic. While VIP port forwarding for HTTP and HTTPS on the same public IP is technically valid—FortiGate supports multiple VIPs with the same external IP as long as the destination ports differ—the VIP itself only defines the translation; a separate firewall policy must explicitly allow the translated traffic. If the policy for port 443 is absent, set to deny, or points to the wrong destination interface or address, the HTTPS packets are dropped before reaching the internal server. On the Fortinet NSE 4 Network Security Professional NSE4 exam, this scenario tests your understanding that VIPs are not self-activating; they require a matching policy with the VIP as the destination. A common trap is assuming that creating the VIP automatically permits traffic, or confusing the VIP configuration with the policy rule. Remember the memory tip: “VIP maps, policy permits—if HTTPS fails, check the policy first.”
NSE4 Firewall Policies and NAT Practice Question
This NSE4 practice question tests your understanding of firewall policies and nat. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
An administrator is configuring a VIP to map a public IP to an internal server. The server hosts both HTTP and HTTPS services. The admin creates a VIP with port forwarding for port 80 to internal port 80, and another VIP for port 443 to internal port 443. Both VIPs use the same public IP. Users can access HTTP but not HTTPS. What is the most likely issue?
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 the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The firewall policy for HTTPS traffic is missing or has incorrect destination
VIPs with the same external IP but different ports should work. However, if no policy allows HTTPS traffic to the VIP, it will be dropped. Alternatively, the VIP configuration might be incomplete.
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 firewall policy for HTTPS traffic is missing or has incorrect destination
Why this is correct
A firewall policy must allow traffic to the VIP. If only HTTP is allowed, HTTPS fails.
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 server's HTTPS service is not running
Why it's wrong here
The question implies users can access HTTP, not HTTPS, so server is reachable.
✗
VIPs cannot share the same public IP address
Why it's wrong here
VIPs can share the same IP if they use different ports.
✗
The HTTPS VIP is configured with the wrong internal port
Why it's wrong here
If internal port were wrong, connection would fail but still be attempted.
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.
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 NSE4 NAT questions on configuration and troubleshooting.
Firewall Policies and NAT — This question tests Firewall Policies and NAT — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The firewall policy for HTTPS traffic is missing or has incorrect destination — VIPs with the same external IP but different ports should work. However, if no policy allows HTTPS traffic to the VIP, it will be dropped. Alternatively, the VIP configuration might be incomplete.
What should I do if I get this NSE4 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 NSE4 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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