Persistent NAT with target host allows external hosts to establish connections only when the internal

device initiates a session first, ideal for specific interactive applications. Refer to Juniper Persistent

NAT Documentation.

The scenario requires that external hosts be able to initiate a connection only if the internal device

has already initiated a connection. The correct solution is Persistent NAT with target host, which

ensures that a specific external host can initiate new connections back to the internal device, but

only after the internal device has established a session first.

Persistent NAT with Target Host (Answer C): This allows the internal device to initiate a connection,

and once established, the specified external host can also initiate new connections to the internal

device on the same NAT mapping.

Example Configuration:

bash

set security nat source persistent-nat permit target-host-port

This solution is appropriate when controlled bidirectional communication is required based on an

internal-initiated connection.

Reference: Juniper persistent NAT documentation.