- A
Decrease the path monitoring interval
Why wrong: Decreasing the interval would increase sensitivity and cause more failovers, not prevent false ones.
- B
HA1 backup link
Why wrong: HA1 backup provides redundancy for the control link, not monitoring.
- C
Enable pre-emptive mode
Why wrong: Pre-emptive mode allows the original active unit to resume after recovery, not related to causing failover.
- D
Use link monitoring instead of path monitoring
Link monitoring only detects physical link failures, so temporary router unreachability would not trigger failover.
Question 235 of 516
How to Prevent False HA Failovers Due to Router Unreachability
This PCNSE practice question tests your understanding of core concepts and architecture. 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.
In an active/passive high-availability pair, the firewall fails over unexpectedly. Investigation shows that the active unit lost connectivity to the upstream router but the link is still up. Which monitoring feature should be configured to prevent false failovers due to temporary router unreachability?
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
✓
Use link monitoring instead of path monitoring
Option D is correct because link monitoring only checks the physical link state of an interface, while path monitoring sends ICMP probes to a target IP address to verify end-to-end reachability. In this scenario, the upstream router is unreachable but the link is still up, so link monitoring would not detect the loss of connectivity and would not trigger a failover. Path monitoring, however, would detect the router unreachability and cause an unnecessary failover, which is exactly the problem described. Therefore, using link monitoring instead of path monitoring prevents false failovers caused by temporary router unreachability.
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.
- ✗
Decrease the path monitoring interval
Why it's wrong here
Decreasing the interval would increase sensitivity and cause more failovers, not prevent false ones.
- ✗
HA1 backup link
Why it's wrong here
HA1 backup provides redundancy for the control link, not monitoring.
- ✗
Enable pre-emptive mode
Why it's wrong here
Pre-emptive mode allows the original active unit to resume after recovery, not related to causing failover.
- ✓
Use link monitoring instead of path monitoring
Why this is correct
Link monitoring only detects physical link failures, so temporary router unreachability would not trigger failover.
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 assume path monitoring is always superior because it checks end-to-end connectivity, but they fail to recognize that it can cause unnecessary failovers during transient network issues, whereas link monitoring is more stable for scenarios where only physical link state matters.
Detailed technical explanation
How to think about this question
Path monitoring in Palo Alto Networks firewalls uses ICMP echo requests to a specified target IP address (e.g., the next-hop router) and triggers a failover if a configurable number of probes fail (default is 10 probes at 3-second intervals). This is useful for detecting upstream failures beyond the local link, but it can cause false failovers during transient routing issues like BGP convergence or brief packet loss. Link monitoring, by contrast, only checks the carrier detect signal on the interface; if the link is up, no failover occurs, making it ideal for scenarios where temporary router unreachability is expected (e.g., during maintenance windows).
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 PCNSE 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.
Visual reference
Quick reference
Routing Protocol Comparison
| Protocol | Metric | Max Hops | Algorithm | Type |
|---|---|---|---|---|
| RIP v2 | Hop count | 15 | Bellman-Ford | Distance vector |
| OSPF | Cost (bandwidth) | Unlimited | Dijkstra (SPF) | Link state |
| EIGRP | Composite metric | Unlimited | DUAL | Hybrid |
| IS-IS | Cost | Unlimited | Dijkstra | Link state |
| BGP | Policy / attributes | Unlimited | Path vector | Path vector |
RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this PCNSE question test?
Core Concepts and Architecture — This question tests Core Concepts and Architecture — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use link monitoring instead of path monitoring — Option D is correct because link monitoring only checks the physical link state of an interface, while path monitoring sends ICMP probes to a target IP address to verify end-to-end reachability. In this scenario, the upstream router is unreachable but the link is still up, so link monitoring would not detect the loss of connectivity and would not trigger a failover. Path monitoring, however, would detect the router unreachability and cause an unnecessary failover, which is exactly the problem described. Therefore, using link monitoring instead of path monitoring prevents false failovers caused by temporary router unreachability.
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.
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 →
Same concept, more angles
1 more ways this is tested on PCNSE
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. An organization runs a pair of Palo Alto Networks firewalls in an active/passive HA configuration. During a maintenance window, the active firewall experiences a link down event on one of its data interfaces. The passive firewall does not assume the active role. What is the most likely reason?
medium- A.HA is configured in active/active mode, which does not support failover on link failure.
- B.The passive firewall has lost its heartbeat connection to the active firewall.
- C.The active firewall has a higher priority value.
- ✓ D.Path monitoring is not configured on the interfaces.
Why D: In an active/passive HA configuration, a link down event on a data interface does not automatically trigger a failover unless path monitoring is configured. Path monitoring allows the firewall to monitor the link state of specific data interfaces and initiate a failover when those interfaces go down. Without path monitoring, the passive firewall remains passive because it only monitors the HA heartbeat and the active firewall's health via the control link, not the data plane link state.
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Last reviewed: Jun 25, 2026
This PCNSE practice question is part of Courseiva's free Palo Alto Networks 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 PCNSE exam.
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