JNCIA-SEC Monitoring And Troubleshooting Practice Question
While analyzing packet flow using security flow traceoptions, you see the message: "ALG: and AlgOpen() failed". What does this indicate?
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 Application Layer Gateway failed to allocate necessary resources or set up dynamic data channels.
Application Layer Gateways (ALGs) handle complex protocols like FTP, SIP, or TFTP. An AlgOpen() failure means the specific ALG failed to allocate resources or open secondary dynamic pinholes.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The primary security policy denied the initial control connection.
Why it's wrong here
If the primary policy denied the packet, the drop happens before ALG processing.
- ✗
The NAT pool was exhausted during source translation.
Why it's wrong here
NAT pool exhaustion generates separate NAT allocation error messages.
- ✓
The Application Layer Gateway failed to allocate necessary resources or set up dynamic data channels.
Why this is correct
This trace message indicates an internal failure within the ALG subsystem while attempting to parse or set up dynamic helper sessions.
- ✗
The destination host refused the TCP connection via a RST packet.
Why it's wrong here
Destination RST packets are handled by standard TCP state machine tracking.
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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.