This PCNSE practice question tests your understanding of core concepts and architecture. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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's dataplane CPU is consistently at 95% utilization even though session count is normal. Analysis shows that a large number of small packets are being processed. Which feature could be causing excessive dataplane processing?
Log forwarding to Panorama
Why wrong: Log forwarding is handled by the management plane.
User-ID agent polling
Why wrong: User-ID polling runs on the management plane, not the dataplane.
Fragmented packet reassembly
Reassembling many small fragmented packets consumes significant dataplane CPU.
SSL Decryption with Forward Proxy
Why wrong: SSL decryption is CPU-intensive but typically handles larger packets, not specifically small packets.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Fragmented packet reassembly
Fragmented packet reassembly forces the dataplane to buffer and reassemble IP fragments before performing security policy checks. This process is CPU-intensive, especially when handling a high volume of small fragments, and can drive dataplane utilization to 95% even when the session count is normal. The firewall must allocate resources to track and reassemble each fragmented datagram, which explains the excessive processing.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Log forwarding to Panorama
Why it's wrong here
Log forwarding is handled by the management plane.
User-ID agent polling
Why it's wrong here
User-ID polling runs on the management plane, not the dataplane.
Fragmented packet reassembly
Why this is correct
Reassembling many small fragmented packets consumes significant dataplane CPU.
Related concept
Read the scenario before looking for a memorised answer.
SSL Decryption with Forward Proxy
Why it's wrong here
SSL decryption is CPU-intensive but typically handles larger packets, not specifically small packets.
Common exam traps
The trap here is that candidates often associate high dataplane CPU with SSL decryption or logging, but the key clue is 'large number of small packets' — a classic indicator of fragmentation-related processing overhead, not encryption or management tasks.
Detailed technical explanation
IP fragmentation is defined in RFC 791, and the firewall must reassemble fragments using a timeout (default 30 seconds) and a reassembly queue per source-destination pair. A flood of small fragments can exhaust the reassembly buffers and cause high CPU due to constant timer management and memory allocation. In real-world scenarios, this is often seen during DDoS attacks using tiny fragments to evade inspection or overwhelm the firewall.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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
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
Core Concepts and Architecture — This question tests Core Concepts and Architecture — Read the scenario before looking for a memorised answer..
The correct answer is: Fragmented packet reassembly — Fragmented packet reassembly forces the dataplane to buffer and reassemble IP fragments before performing security policy checks. This process is CPU-intensive, especially when handling a high volume of small fragments, and can drive dataplane utilization to 95% even when the session count is normal. The firewall must allocate resources to track and reassemble each fragmented datagram, which explains the excessive processing.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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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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