The correct answer is that the HTTPS request is allowed by the rule Allow_Web because the service tcp/443 matches. This occurs because Palo Alto Networks security rules evaluate traffic by checking both the application and the service object; here, the application ssl matches the HTTPS traffic, and the service object tcp/443 explicitly matches the destination port, so the rule permits the connection. On the PCNSA exam, this scenario tests your understanding of how service objects narrow rule matching beyond just application identification—a common trap is assuming application alone determines the match, but the service object must also align for the rule to apply. Remember that a rule with a specific service like tcp/443 will only match traffic on that exact port, even if the application is correct, so always verify both fields. A helpful memory tip is “App for what, service for where”—the application identifies the protocol, while the service specifies the port.
PCNSA Securing Traffic Practice Question
This PCNSA practice question tests your understanding of securing traffic. 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.
Exhibit
Refer to the exhibit.
Exhibit: CLI output from 'show running security-policy' shows:
```
set rulebase security rules "Allow_Web" from untrust to dmz source any destination 10.1.1.0/24 application web-browsing,ssl service tcp/80, tcp/443 action allow log-end
set rulebase security rules "Block_ALL" from any to any source any destination any application any service any action deny
```
Based on the exhibit, what will happen to an HTTPS request from an untrust zone user to destination IP 10.1.1.50?
Refer to the exhibit.
Exhibit: CLI output from 'show running security-policy' shows:
```
set rulebase security rules "Allow_Web" from untrust to dmz source any destination 10.1.1.0/24 application web-browsing,ssl service tcp/80, tcp/443 action allow log-end
set rulebase security rules "Block_ALL" from any to any source any destination any application any service any action deny
```
A
Denied because the source is not specified in Allow_Web.
Why wrong: The rule specifies source any, so all sources from untrust are matched.
B
Denied by rule Block_ALL because it is the last rule.
Why wrong: The traffic matches the first rule Allow_Web, so it is allowed and never reaches Block_ALL.
C
Allowed by rule Allow_Web because service tcp/443 matches.
HTTPS uses tcp/443, and the rule allows that service along with application ssl.
D
Allowed by rule Allow_Web because application ssl matches.
Why wrong: Although ssl matches, the service tcp/443 also matches and is more explicit in this context.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Allowed by rule Allow_Web because service tcp/443 matches.
Option C is correct. The rule Allow_Web has application ssl which matches HTTPS, and service tcp/443 matches. So the traffic is allowed. Option A is partially correct but best answer is C because service is explicitly matched. Option B is not hit as the traffic matches Allow_Web first. Option D is incorrect because source is any.
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.
✗
Denied because the source is not specified in Allow_Web.
Why it's wrong here
The rule specifies source any, so all sources from untrust are matched.
✗
Denied by rule Block_ALL because it is the last rule.
Why it's wrong here
The traffic matches the first rule Allow_Web, so it is allowed and never reaches Block_ALL.
✓
Allowed by rule Allow_Web because service tcp/443 matches.
Why this is correct
HTTPS uses tcp/443, and the rule allows that service along with application ssl.
Related concept
Static NAT maps one inside address to one outside address.
✗
Allowed by rule Allow_Web because application ssl matches.
Why it's wrong here
Although ssl matches, the service tcp/443 also matches and is more explicit in this context.
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 PCNSA NAT questions on configuration and troubleshooting.
Securing Traffic — This question tests Securing Traffic — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Allowed by rule Allow_Web because service tcp/443 matches. — Option C is correct. The rule Allow_Web has application ssl which matches HTTPS, and service tcp/443 matches. So the traffic is allowed. Option A is partially correct but best answer is C because service is explicitly matched. Option B is not hit as the traffic matches Allow_Web first. Option D is incorrect because source is any.
What should I do if I get this PCNSA 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 PCNSA NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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