PCNSE Deploy and Configure Firewalls Practice Question
This PCNSE practice question tests your understanding of deploy and configure firewalls. 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.
A global company uses a pair of PAN-220 firewalls in an active/passive HA configuration at its headquarters. The firewalls have multiple virtual routers and dozens of zones. Recently, a network upgrade changed the physical topology: a new switch was placed between the firewalls and the ISP routers. After the upgrade, the passive firewall continuously shows 'suspended' state. The HA control link (HA1) and data link (HA2) are on separate dedicated interfaces. The Active firewall logs show: 'HA monitor peer unreachable' every few seconds. The engineer has verified IP connectivity between the HA interfaces using ping from the active to the passive HA1 IP. What is the most likely cause of the HA state 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 new switch introduces latency or jitter that exceeds the HA keepalive timeout
The 'HA monitor peer unreachable' log combined with a 'suspended' passive firewall, despite confirmed IP connectivity on HA1, points to a failure in the HA keepalive mechanism. The new switch introduces latency or jitter that causes keepalive packets to arrive outside the default 2-second hello interval and 8-second dead-interval, triggering the active firewall to declare the peer unreachable. This is a classic issue when a switch is inserted into the HA path without adjusting the HA keepalive timers or ensuring the switch provides low-latency forwarding.
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 HA2 link is misconfigured or unplugged
Why it's wrong here
HA2 is for data; the 'suspended' state is driven by HA1 heartbeat failures.
✓
The new switch introduces latency or jitter that exceeds the HA keepalive timeout
Why this is correct
HA keepalives are time-sensitive; a switch can add latency that makes the passive appear dead, even if basic connectivity exists.
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.
✗
The session table on the active firewall is full, preventing HA keepalives
Why it's wrong here
Session table fullness may cause performance issues but does not directly stop HA keepalive packets.
✗
The HA1 encryption setting is mismatched between the two firewalls
Why it's wrong here
Mismatched encryption would show a different log, not simply 'peer unreachable'.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume ping success between HA interfaces guarantees HA keepalive success, but HA keepalives are more sensitive to jitter and latency than ICMP, and the 'suspended' state specifically indicates a keepalive timeout rather than a link or encryption failure.
Trap categories for this question
Command / output trap
Mismatched encryption would show a different log, not simply 'peer unreachable'.
Detailed technical explanation
How to think about this question
HA keepalives use UDP port 2920 on the HA1 link and are sent every 2 seconds by default; if four consecutive keepalives are missed (8-second dead interval), the peer is marked unreachable. Inserting a switch adds propagation delay, queuing delay, and potential microbursts, which can cause jitter exceeding the dead interval, especially if the switch is not configured with strict priority queuing for control traffic. In real-world scenarios, engineers often overlook the need to configure the switchport as an access port with no spanning-tree or to enable 'ha1-keepalive' timer adjustments (e.g., 'set deviceconfig high-availability keepalive-backup hello-interval 1') to compensate for added latency.
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.
Deploy and Configure Firewalls — This question tests Deploy and Configure Firewalls — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The new switch introduces latency or jitter that exceeds the HA keepalive timeout — The 'HA monitor peer unreachable' log combined with a 'suspended' passive firewall, despite confirmed IP connectivity on HA1, points to a failure in the HA keepalive mechanism. The new switch introduces latency or jitter that causes keepalive packets to arrive outside the default 2-second hello interval and 8-second dead-interval, triggering the active firewall to declare the peer unreachable. This is a classic issue when a switch is inserted into the HA path without adjusting the HA keepalive timers or ensuring the switch provides low-latency forwarding.
What should I do if I get this PCNSE 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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