JNCIA-SEC Network Address Translation Practice Question
You are reviewing a Junos configuration containing both Destination NAT and Static NAT. An incoming packet matches both a Destination NAT rule and a Static NAT rule. Based on Junos OS NAT processing architecture, how is this conflict handled?
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
✓
Destination NAT is evaluated first; if a match occurs, the packet is translated by Destination NAT and subsequent NAT stages are skipped for that transformation stage.
Junos OS evaluates Destination NAT first and Static NAT last. However, within distinct processing pipelines, a packet is evaluated against rule sets in order. Destination NAT rule-sets are evaluated before Static NAT rule-sets. If a packet matches a Destination NAT rule, that NAT is applied and evaluation for that stage finishes.
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 SRX device generates a syntax error upon commit if overlapping Destination and Static NAT rules exist.
Why it's wrong here
Junos allows both rule sets to be configured, relying on the strict evaluation order rather than rejecting the commit.
- ✗
Both translations are applied simultaneously, resulting in double destination translation.
Why it's wrong here
A packet is only subjected to one primary destination translation stage per flow setup.
- ✓
Destination NAT is evaluated first; if a match occurs, the packet is translated by Destination NAT and subsequent NAT stages are skipped for that transformation stage.
Why this is correct
Since Destination NAT is evaluated before Static NAT in the processing sequence, the matching Destination NAT rule takes precedence.
- ✗
Static NAT takes precedence over Destination NAT because it provides a bidirectional mapping.
Why it's wrong here
Destination NAT is evaluated before Static NAT in Junos rule evaluation order.
Visual reference
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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.