JNCIA-SEC Monitoring And Troubleshooting Practice Question
An administrator enables security flow traceoptions to debug a packet drop. The log file shows the drop reason as "No session found; policy check failed". What is the most likely cause of this error?
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
✓
The packet is the first packet of a new flow, and no matching security policy permits the traffic.
When a packet does not match an existing session, the SRX evaluates security policies. If no policy permits the traffic, a drop occurs with an explicit policy check failure message.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
NAT pool exhaustion prevented session creation.
Why it's wrong here
NAT pool exhaustion results in NAT allocation failure logs.
- ✗
The session table is full and cannot allocate memory for a new session.
Why it's wrong here
Session table exhaustion generates a distinct resource depletion log message.
- ✓
The packet is the first packet of a new flow, and no matching security policy permits the traffic.
Why this is correct
Initial packets require a matching permit security policy; if none matches, the flow is rejected or denied.
- ✗
The packet belongs to an established TCP connection whose sequence number was invalid.
Why it's wrong here
Invalid sequence numbers result in TCP RST or packet drop due to sequence number mismatch, not a policy check failure.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed August 2026 · checked against the official Juniper Networks exam blueprint
This JNCIA-SEC practice question is part of Courseiva's free Juniper 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 JNCIA-SEC exam.