On Juniper SRX Series devices, Network Address Translation (NAT) types are processed with a specific order of precedence to resolve conflicts when a packet matches multiple NAT rules. Static NAT has the highest precedence because it creates a specific, bi-directional, one-to-one mapping. If a packet's destination address matches both a static NAT rule and a destination NAT rule, the static NAT rule will be applied. This ensures that specific, statically defined translations are always honored over more general, pool-based destination translations.

A. Destination NAT takes precedence over static NAT. This is incorrect. Juniper's NAT processing hierarchy explicitly gives static NAT higher precedence than destination NAT.

B. Source NAT is processed before security policy lookup. This is incorrect. In the Junos packet flow, source NAT is processed after the security policy lookup, just before the packet egresses the device.

C. Static NAT is processed after forwarding lookup. This is incorrect. Static NAT (and destination NAT) is processed before the forwarding (route) lookup so that the routing decision is based on the translated destination address.

1. Juniper Networks TechLibrary

NAT Overview: "For packets entering the security device

NAT rule lookup for static NAT and destination NAT is done before the route lookup... Static NAT has a higher priority than destination NAT."

URL: https://www.juniper.net/documentation/us/en/software/junos/nat/topics/concept/nat-overview.html (See the "NAT Processing" section).

2. Juniper Networks TechLibrary

Understanding NAT Packet Flow: This document provides a detailed diagram and explanation of the packet processing order. It shows that Static NAT and Destination NAT occur in the "Flow lookup/create session" phase

which is before the "Route lookup" and "Policy lookup". Source NAT occurs later

after the policy check.

URL: https://www.juniper.net/documentation/us/en/software/junos/nat/topics/concept/nat-packet-flow-understanding.html (Refer to the packet flow diagram and description).