PCNSE Manage, Monitor and Operate Practice Question
A network security engineer is investigating why a firewall's dataplane CPU is consistently at 95%. After reviewing the session table, they notice a large number of sessions in a 'discard' state. Which action should the engineer take first to resolve the high CPU utilization?
⚠ Common exam trap
The trap here is assuming that session timeouts or hardware offload are the primary causes of high CPU due to discard sessions.
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
✓
Check the security policy for a rule that denies traffic without sending a response.
Sessions in a discard state are often caused by a security policy rule that silently drops traffic without sending a response. This can lead to a large number of sessions lingering in the session table, consuming dataplane CPU. Reviewing and adjusting the security policy to send resets or ICMP unreachable messages can help clear these sessions more quickly and reduce CPU utilization.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Reduce the TCP handshake timeout value.
Why it's wrong here
The TCP handshake timeout controls how long a session can remain in a SYN state. Sessions in a discard state are not necessarily in a handshake phase; they are typically established sessions that are being dropped. Reducing the handshake timeout would not affect discard-state sessions and could cause legitimate connections to fail if set too low.
- ✓
Check the security policy for a rule that denies traffic without sending a response.
Why this is correct
Sessions in a discard state often result from a security policy rule with an action of 'deny' and no notification to the client, such as a 'drop' action. When the firewall silently drops packets, sessions may linger until they time out, consuming resources. Reviewing the security policy to identify such rules and adjusting them to send a reset or ICMP unreachable can clear sessions faster and reduce CPU load.
- ✗
Increase the session timeout for TCP sessions.
Why it's wrong here
Increasing the session timeout would allow sessions to remain in the session table longer, potentially exacerbating the issue by consuming more resources. Sessions in a discard state are typically waiting to be discarded due to policy or other reasons; extending timeouts would not address the root cause and could increase CPU load by keeping more sessions active.
- ✗
Enable hardware offload for session setup.
Why it's wrong here
Hardware offload can improve performance for certain traffic types, but it does not directly address sessions stuck in a discard state. The discard state often indicates that the firewall is dropping packets due to a policy action or resource constraint. Enabling offload without identifying the cause may not resolve the high CPU and could mask the underlying issue.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Palo Alto Networks exam blueprint
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.