JNCIA-SEC Network Address Translation Practice Question
You are troubleshooting a complex Static NAT setup where an internal mail server (10.10.10.5) is mapped to a public IP (198.51.100.5). External inbound connections work, but outbound connections initiated from the mail server show that the source IP is being translated by a general interface-based Source NAT rule rather than the Static NAT mapping. How do you ensure outbound connections from the mail server use its Static NAT public IP?
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
✓
Ensure that conflicting Source NAT rules are placed lower in evaluation order or exclude the mail server IP from the Source NAT rule-set match criteria.
In Junos OS, static NAT automatically provides bidirectional translation (both inbound destination and outbound source translation). However, if a more specific Source NAT rule matches the traffic first (due to rule ordering or overlapping source rules), the Source NAT rule takes precedence over the implicit static NAT source translation. The administrator must adjust rule ordering or ensure source NAT rules do not override the static NAT host.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Explicitly configure a Source NAT rule that maps the mail server IP to its own public IP address.
Why it's wrong here
Static NAT already handles source translation implicitly; adding a redundant source NAT rule adds unnecessary configuration complexity and potential rule conflicts.
- ✗
Disable interface-based source NAT globally and migrate all internal subnets to pool-based NAT.
Why it's wrong here
Disabling interface-based NAT globally impacts all other traffic unnecessarily.
- ✗
Change the static NAT rule to operate as a destination-only NAT pool.
Why it's wrong here
Destination NAT is unidirectional; changing static NAT to destination-only would break inbound/outbound symmetry.
- ✓
Ensure that conflicting Source NAT rules are placed lower in evaluation order or exclude the mail server IP from the Source NAT rule-set match criteria.
Why this is correct
Explicit Source NAT rules take precedence over static NAT if they match the traffic; excluding the host or reordering rules resolves this.
Visual reference
About these practice questions
This JNCIA-SEC question is part of Courseiva's 520-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.