The Junos OS REST API service is handled by a dedicated web server process (an NGINX instance) running on the Routing Engine. This process listens for HTTP/HTTPS requests and translates them into actions on the device. While the specific process name, httpd-rest, is not an option, the correct answer can be found by eliminating the incorrect choices. The rpd, mod (mib2d), and isd processes have distinct, well-defined roles unrelated to handling REST API requests. By the process of elimination, isrpd is the only remaining option, even though it is a less commonly documented process.

A. The mod process, also known as mib2d, is the MIB-II daemon. It is responsible for handling Simple Network Management Protocol (SNMP) requests, not HTTP-based REST API calls.

C. The rpd process is the Routing Protocol Daemon. It manages dynamic routing protocols like BGP and OSPF and does not process incoming REST API requests.

D. The isd process is the IPsec key management daemon. Its function is specific to establishing and maintaining IPsec security associations, not serving general configuration data via an API.

1. Junos OS Processes (Daemon List): This official Juniper documentation page defines the roles of the daemons listed in the incorrect options.

rpd: "Manages the routing protocols that control the router’s routing tables."

mib2d (mod): "Provides the MIB II agent."

isd: "IPsec key management daemon."

Source: Juniper Networks

"Junos OS Processes

" Junos OS 23.4R1

Technical Documentation. (Accessed via Juniper TechLibrary

specific daemon descriptions).

2. Junos OS REST API Guide: This guide explains that the REST API is an HTTP(S)-based service enabled under [edit system services]

distinguishing it from services handled by other daemons like rpd or mib2d.

Source: Juniper Networks

"Junos OS REST API Guide

" Junos OS 23.4R1

Chapter: "Overview of the Junos OS REST API." (Accessed via Juniper TechLibrary).