- A
show counter global | match drop
Why wrong: This shows drop counters but doesn't identify the source of an attack.
- B
show session all | match <source IP>
This command lists all sessions and can be filtered to see if a single source has many sessions.
- C
request high-availability state
Why wrong: This command is for HA state, not troubleshooting CPU utilization.
- D
debug flow basic
Why wrong: Debug flow basic is used for packet flow debugging, not for identifying high session counts.
Question 10 of 516
Identify DoS Attack Source: Show Session All Command
This PCNSE practice question tests your understanding of troubleshoot. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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 firewall is experiencing high CPU utilization. The engineer suspects a denial-of-service attack. Which command should be used to identify the source of the attack?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"which command"Why it matters: Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
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
✓
show session all | match <source IP>
Option B is correct because the 'show session all' command displays all active sessions on the firewall, and piping the output to 'match <source IP>' filters for sessions originating from a specific IP address. In a high CPU scenario suspected to be a DoS attack, this allows the engineer to quickly identify if a single source IP is generating an excessive number of sessions, which is a common indicator of a flood-based attack.
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.
- ✗
show counter global | match drop
Why it's wrong here
This shows drop counters but doesn't identify the source of an attack.
- ✓
show session all | match <source IP>
Why this is correct
This command lists all sessions and can be filtered to see if a single source has many sessions.
Clue confirmation
The clue word "which command" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
request high-availability state
Why it's wrong here
This command is for HA state, not troubleshooting CPU utilization.
- ✗
debug flow basic
Why it's wrong here
Debug flow basic is used for packet flow debugging, not for identifying high session counts.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often choose 'debug flow basic' (option D) because they think deep packet inspection is needed to find the attack source, but this command is too resource-intensive and does not directly identify the source IP; instead, the session table query is the correct first step.
Trap categories for this question
Command / output trap
This shows drop counters but doesn't identify the source of an attack.
Detailed technical explanation
How to think about this question
Under the hood, the 'show session all' command queries the session table in the firewall's dataplane, which stores 5-tuple information (source IP, destination IP, source port, destination port, protocol) for each active session. During a DoS attack, the session table may fill with half-open or flood sessions from a single IP; filtering by source IP reveals the offending host. In real-world scenarios, an attacker may spoof source IPs, so combining this with 'show session all | count' can reveal the total session count per IP, and 'show running resource-monitor' can confirm CPU impact from session table exhaustion.
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.
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.
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FAQ
Questions learners often ask
What does this PCNSE question test?
Troubleshoot — This question tests Troubleshoot — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: show session all | match <source IP> — Option B is correct because the 'show session all' command displays all active sessions on the firewall, and piping the output to 'match <source IP>' filters for sessions originating from a specific IP address. In a high CPU scenario suspected to be a DoS attack, this allows the engineer to quickly identify if a single source IP is generating an excessive number of sessions, which is a common indicator of a flood-based attack.
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: "which command". Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jul 4, 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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