JNCIA-SEC Network Address Translation Practice Question
An administrator has configured multiple rules within a single Source NAT rule-set. When traffic traverses the SRX device, how does Junos OS determine which specific rule within the rule-set is applied?
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
✓
Rules are evaluated top-down; the first rule matching the packet's criteria is applied.
Rules within a Junos NAT rule-set are evaluated in top-down order (the order in which they were created or inserted). The first rule whose match criteria (source address, destination address, applications, etc.) match the packet is applied.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Rules are evaluated top-down; the first rule matching the packet's criteria is applied.
Why this is correct
Junos processes NAT rules sequentially from top to bottom, stopping at the first match.
- ✗
Rules are evaluated based on specificity; the most specific match is always applied regardless of configuration order.
Why it's wrong here
Unlike some firewall architectures, Junos evaluates NAT rules strictly in the configured sequential order, not via longest-match algorithm.
- ✗
Rules are evaluated using hashing algorithms to distribute translation loads evenly across rules.
Why it's wrong here
NAT rule evaluation does not use hashing; it uses sequential rule matching.
- ✗
All matching rules are combined, and translations are applied concurrently.
Why it's wrong here
Only the first matching rule is applied to a given session flow.
Visual reference
About these practice questions
This JNCIA-SEC question is part of Courseiva's 513-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
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.