The answer is that the internal interface (ethernet1/2) is administratively down. This is the most likely cause because an interface placed in an admin down state will not pass any traffic, regardless of how permissive the security policy or routing table may be; the firewall physically drops all packets at the interface level before they can be evaluated. On the Palo Alto Networks Certified Network Security Administrator PCNSA exam, this scenario tests your understanding that interface operational status overrides all higher-level configurations—a common trap is to focus on policy misconfigurations or routing issues when the root cause is a simple administrative shutdown. Remember the memory tip: “Admin down, traffic drowns”—if the interface isn’t up, no packet can enter or exit, making it the first thing to check when troubleshooting no internet access because interface admin down Palo Alto.
PCNSA Device Management and Services Practice Question
This PCNSA practice question tests your understanding of device management and services. 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.
Exhibit
> show system info
hostname: PA-5250
model: PA-5250
sw-version: 10.1.3
app-version: 8340-5987
threat-version: 8340-5987
> show running ip-route
destination: 0.0.0.0/0
nexthop: 10.0.0.1
interface: ethernet1/1
> show interface ethernet1/1
interface: ethernet1/1
state: up
ip address: 10.0.0.2/24
zone: external
> show interface ethernet1/2
interface: ethernet1/2
state: down
ip address: 192.168.1.1/24
zone: internal
Refer to the exhibit. A firewall has the configuration shown. A security policy allows traffic from the internal zone to the external zone. However, users on the internal network (192.168.1.0/24) cannot reach the internet. What is the most likely cause?
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.
> show system info
hostname: PA-5250
model: PA-5250
sw-version: 10.1.3
app-version: 8340-5987
threat-version: 8340-5987
> show running ip-route
destination: 0.0.0.0/0
nexthop: 10.0.0.1
interface: ethernet1/1
> show interface ethernet1/1
interface: ethernet1/1
state: up
ip address: 10.0.0.2/24
zone: external
> show interface ethernet1/2
interface: ethernet1/2
state: down
ip address: 192.168.1.1/24
zone: internal
A
The internal interface has no IP address assigned
Why wrong: The IP address 192.168.1.1/24 is assigned.
B
The internal zone is not configured
Why wrong: The interface shows zone: internal, so it is configured.
C
The default route is missing
Why wrong: The show running ip-route shows a default route to 10.0.0.1.
D
The internal interface (ethernet1/2) is administratively down
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The internal interface (ethernet1/2) is administratively down
Option D is correct because the exhibit shows that ethernet1/2, which is the internal interface, is administratively down (status 'admin down'). An administratively down interface does not pass any traffic, regardless of security policies or routing. Even with a correct security policy allowing internal-to-external traffic, the interface must be operationally up for packets to enter or leave the firewall.
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.
✗
The internal interface has no IP address assigned
Why it's wrong here
The IP address 192.168.1.1/24 is assigned.
✗
The internal zone is not configured
Why it's wrong here
The interface shows zone: internal, so it is configured.
✗
The default route is missing
Why it's wrong here
The show running ip-route shows a default route to 10.0.0.1.
✓
The internal interface (ethernet1/2) is administratively down
Why this is correct
The interface must be up for traffic to pass.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often overlook the interface administrative state and instead focus on routing or security policy misconfigurations, assuming that a configured IP and zone guarantee traffic flow.
Trap categories for this question
Command / output trap
The interface shows zone: internal, so it is configured.
Detailed technical explanation
How to think about this question
In Palo Alto Networks firewalls, an interface in 'admin down' state is manually disabled via the 'shutdown' command in the CLI or by unchecking 'Enable' in the GUI. This state is independent of the link status (L1) and prevents all Layer 2 and Layer 3 processing. To verify, an engineer would use 'show interface ethernet1/2' and look for 'Admin State: down'. In contrast, a missing default route would cause traffic to be dropped at the routing stage, but the interface would still show 'up' and could forward traffic within the connected subnet.
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 practitioner preparing for the PCNSA exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
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.
Device Management and Services — This question tests Device Management and Services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The internal interface (ethernet1/2) is administratively down — Option D is correct because the exhibit shows that ethernet1/2, which is the internal interface, is administratively down (status 'admin down'). An administratively down interface does not pass any traffic, regardless of security policies or routing. Even with a correct security policy allowing internal-to-external traffic, the interface must be operationally up for packets to enter or leave the firewall.
What should I do if I get this PCNSA question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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?
Read the scenario before looking for a memorised answer.
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Question Discussion
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