JNCIA-SEC Network Address Translation Practice Question
When configuring Proxy ARP for Static NAT or Destination NAT on an SRX Series device, which THREE operational or configuration practices must be considered? (Choose three)
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
✓
Proxy ARP must be enabled on the external interface facing the upstream router.
Proxy ARP requires proper interface association, matching public IP subnets reachable by the upstream router, and enabling it on the external interface.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Proxy ARP must be enabled on the external interface facing the upstream router.
Why this is correct
The SRX must reply to ARP requests for public NAT IPs on its external interface.
- ✓
The public IP addresses used in static/destination NAT must align with the subnet connected to the external interface.
Why this is correct
Upstream routers send ARP requests for IPs within their connected subnet; proxy ARP responds accordingly.
- ✗
Proxy ARP automatically performs port address translation for ICMP packets.
Why it's wrong here
Proxy ARP is strictly Layer 2 ARP resolution and does not handle Layer 4 port translation.
- ✓
Proxy ARP eliminates the need for static routes on upstream routers for those public IPs.
Why this is correct
Proxy ARP allows the SRX to claim ownership of the public IPs via ARP without requiring specific host routes upstream.
- ✗
Proxy ARP is required for internal trusted interface clients accessing local servers.
Why it's wrong here
Proxy ARP is for external interfaces, not internal trusted clients.
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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.