JNCIA-SEC Srx Series Service Gateways Practice Question
An administrator configures NAT on an SRX Series gateway and encounters an issue where overlapping IP spaces require destination NAT and source NAT (twice NAT) simultaneously. In what order are NAT rules evaluated in the SRX packet flow?
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 before routing and security policy lookup, while Source NAT is evaluated later in the flow pipeline
Destination NAT is evaluated first on incoming packets before routing lookup, while source NAT is evaluated later in the packet flow outbound.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Both NAT types are evaluated simultaneously in a single processing step.
Why it's wrong here
They occur at different stages of the SRX packet flow pipeline.
- ✗
NAT rules are only evaluated after session termination.
Why it's wrong here
NAT must be evaluated when establishing the session.
- ✗
Source NAT is evaluated before Destination NAT
Why it's wrong here
Destination NAT happens prior to routing and security policy lookups, whereas source NAT happens later.
- ✓
Destination NAT is evaluated before routing and security policy lookup, while Source NAT is evaluated later in the flow pipeline
Why this is correct
Destination NAT modifies the destination IP before the routing lookup, and source NAT is applied on egress/session creation.
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.