Junos OS provides two primary Application Programming Interfaces (APIs) for scripts and applications running directly on the device (on-box). The Junos XML API is the foundational interface, representing all configuration and operational data in an XML format. On-box scripts, such as those written in SLAX, XSLT, and Python, use this API to interact with the device's state. The Junos Extension Toolkit (JET) is a more modern framework that provides a set of high-performance APIs, often over gRPC, for developing on-box applications (typically in Python) that can directly interface with various Junos processes for advanced control and telemetry.

B. Puppet: Puppet is an off-box configuration management tool that pushes configurations to Junos devices; it is not an API for scripts running on the device itself.

D. Chef: Similar to Puppet, Chef is an off-box automation framework used to manage Junos devices remotely, not an on-box scripting API.

1. Junos Extension Toolkit (JET) Developer Guide. Juniper Networks. "JET Overview." This guide states

"You can develop JET applications to run on a Juniper Networks device (on-box) or on a remote server (off-box). JET applications use APIs to interact with Junos OS." This confirms JET as an on-box API.

2. Junos XML API and Scripting Developer Guide. Juniper Networks. "Junos XML API Overview." This document explains

"The Junos XML API is a programmatic interface for requesting and modifying information on a device running Junos OS... On-box scripts use the Junos XML API to perform custom functions on the device." This confirms the XML API's role in on-box scripting.

3. Automation Scripting User Guide. Juniper Networks. "Overview of Automation Scripting." This guide details the use of on-box scripts (SLAX

XSLT

Python) and their interaction with the Junos XML hierarchy

reinforcing the XML API as central to on-box scripting.

4. Understanding Puppet for Junos OS. Juniper Networks. "Puppet for Junos OS Architecture." This document describes the architecture where a Puppet master server manages Junos devices

which act as clients. This clearly defines Puppet as an off-box management solution.