JNCIA-SEC Network Address Translation Practice Question
You are troubleshooting a scenario where an SRX Series device is performing Destination NAT. You notice that sessions are being created in the flow table, but the translation is failing because the packet hits a rule in a different rule-set. How does Junos OS evaluate multiple Destination NAT rule-sets?
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
✓
Rule-sets are evaluated in the order they appear in the configuration; the first matching rule-set and rule are applied.
Junos OS evaluates Destination NAT rule-sets based on top-down order within the configuration hierarchy or based on specific zone matches. When multiple rule-sets exist, the SRX evaluates them sequentially until a matching rule-set and rule is found.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
All matching rule-sets are applied in parallel, which can cause translation conflicts.
Why it's wrong here
Only the first matching rule-set and rule are applied to a session.
- ✓
Rule-sets are evaluated in the order they appear in the configuration; the first matching rule-set and rule are applied.
Why this is correct
Junos evaluates NAT rule-sets sequentially as ordered in the configuration database.
- ✗
Rule-sets are evaluated based on the most specific destination IP address match across all rule-sets simultaneously.
Why it's wrong here
Junos does not evaluate rule-sets simultaneously via a global longest-match algorithm; order in configuration matters.
- ✗
Destination NAT rule-sets are evaluated alphabetically by rule-set name.
Why it's wrong here
Evaluation order follows configuration hierarchy sequence, not alphabetical order.
Visual reference
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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.