JN0-223 Automation and DevOps Associate (JNCIA-DevOps) Questions and Answers

Junos on-box scripting supports the following programming languages:

SLAX (C): SLAX (Structured Language for XML) is a scripting language designed specifically for Junos devices. It allows for easy manipulation of XML data, making it ideal for creating Junos scripts that interact with device configurations.

XSLT (D): XSLT (Extensible Stylesheet Language Transformations) is another language used for transforming XML documents into other formats. It is commonly used in Junos for transforming XML data into different views or outputs.

Options A (Perl) and B (Ruby) are not used for Junos on-box scripting.While these languages are popular in other contexts, Junos scripting relies heavily on XML-based languages like SLAX and XSLT.

Junos XML API and Scripting Guide: Describes the use of SLAX and XSLT for on-box scripting.

Juniper Networks Automation Documentation: Provides examples and best practices for using SLAX and XSLT in Junos scripting.

References:

NETCONF (Network Configuration Protocol) operates through different layers, with the operations layer being particularly important for managing configurations:

Operations Layer (A & D): This layer is responsible for actions like locking and committing the configuration on a Junos device. The lock operation prevents other sessions from modifying the configuration, and the commit operation applies the configuration changes to the device.

Options B and Care incorrect because the messages layer handles the communication aspects, such as exchanging data between the client and server, not performing configuration operations like locking and committing.

IETF RFC 6241 (NETCONF): Describes the protocol layers and their functions, with a focus on the operations layer.

Juniper Networks NETCONF Documentation: Provides insights into how NETCONF operations are managed in Junos

References:

In the context of the DevOps "Three Ways" principles, thefeedbackprinciple directly addresses the management of technical debt.

The "Three Ways" are core principles guiding DevOps practices, and they are as follows:

Flow:Refers to the smooth and fast flow of work through the system, from development to operations.

Feedback:Emphasizes creating effective, fast, and continuous feedback loops between teams to catch issues early, address technical debt, and ensure quality.

Continuous experimentation and learning:Encourages constant experimentation, innovation, and learning from failures to improve systems and processes over time.

Feedback and Technical Debt:

Feedbackloops play a crucial role in addressing technical debt. Technical debt refers to the implied cost of additional work that arises when code or system design decisions are made for short-term gains, such as quick fixes or temporary patches. Over time, technical debt can accumulate and degrade system performance, reliability, and maintainability.

Thefeedback loopensures that issues related to technical debt (such as poor code quality, design shortcuts, or performance bottlenecks) are caught early in the process, ideally before they become major problems. Continuous monitoring, testing, and reviewing help identify and resolve technical debt incrementally rather than letting it accumulate unchecked.

Automation in feedback loops: In DevOps, automated testing, continuous integration (CI), and monitoring tools provide immediate feedback to developers, highlighting areas where technical debt is increasing. This feedback is crucial for making proactive decisions about refactoring code or improving infrastructure without waiting for problems to manifest in production.

For instance, the feedback loop might expose slowdowns in application performance after each new feature is added. This would trigger a review to either refactor the feature code or improve system resources, preventing further technical debt accumulation.

Flow and Technical Debt:

Whileflowfocuses on the smooth transition of work through the pipeline, it indirectly helps with technical debt by ensuring continuous and streamlined processes. However, feedback mechanisms are the primary tools for identifying and resolving technical debt.

Continuous Experimentation and Learning:

This principle promotes innovation and learning from failures but does not directly address technical debt. The focus here is more on risk-taking and improvement rather than managing or eliminating technical debt.

References from DevOps Practices:

The Phoenix Project, a book often referenced in DevOps, discusses how feedback loops are essential for maintaining system integrity and managing technical debt effectively. By improving feedback mechanisms, teams can address small issues before they become costly to fix.

The DevOps Handbookalso highlights the importance of feedback in managing technical debt, emphasizing that fast feedback allows for continuous improvement and avoids the accumulation of bad practices that would otherwise lead to technical debt.

Juniper Automation and DevOps Context:Juniper’s automation frameworks integrate feedback mechanisms using tools like continuous monitoring and automated testing. These tools help engineers track the health of network systems, identify configuration drifts, and resolve issues before they lead to significant technical debt.

Additional Resources:

The Phoenix Project by Gene Kim

The DevOps Handbook

Two important aspects of the DevOps culture are:

Communication (A): In a DevOps environment, continuous and effective communication between development, operations, and other stakeholders is crucial. It ensures that everyone is aligned, reduces misunderstandings, and facilitates faster and more efficient workflows.

People (D): DevOps is as much about the people as it is about the processes and tools. The culture emphasizes collaboration, shared responsibility, and a mindset focused on continuous improvement. Empowering people to work together across different disciplines is at the heart of DevOps.

Options B and C are not primary aspects of the DevOps culture. While tools are essential in implementing DevOps practices, the culture emphasizes communication and collaboration among people more than the use of specific tools or rigid separation of duties.

DevOps Handbook: Discusses the cultural aspects of DevOps, with a focus on communication and people.

DevOps Best Practices: Highlights the importance of fostering a culture that prioritizes collaboration and shared goals.

References:

Juniper Networks' Junos operating system supports several APIs for on-box scripting, two of which are:

JET (Juniper Extension Toolkit): JET is a modern API framework that provides a programmable interface for interacting with Junos. It allows developers to create custom applications that run directly on Junos devices, enabling the automation of network operations. JET provides both a gRPC and a REST API interface, allowing for flexible integration with external systems.

XML API: The Junos XML API allows direct interaction with the Junos OS through XML-based requests. This API can be used to retrieve information, configure devices, and execute commands on Junos devices. The XML API is crucial for automation tasks as it provides a structured and consistent way to interact with the device's configuration and operational data.

JET (A)provides high-performance access to Junos routing, switching, and service elements via programmable interfaces. It is highly used for creating custom applications that require tight integration with the Junos OS.

XML (C), on the other hand, is a well-established method for interacting with Junos, especially for legacy systems or when working within environments where XML is the standard data format.

Detailed Explanation:Other options like Puppet (B) and Chef (D) are not APIs provided by Junos for on-box scripting but are configuration management tools used externally to manage Junos devices.

Juniper Networks JET Documentation: Provides details on how to leverage JET APIs for automation.

Junos XML Management Protocol Guide: Describes how to use XML for scripting and automating tasks in Junos.

References:These APIs are key components of Juniper's automation strategy, allowing for scalable, flexible, and efficient network operations.

In Python, the correct syntax to prompt the user for input and store that input in a variable is:

input(prompt): Theinput()function is used to take input from the user. The string provided as an argument (inside the parentheses) is displayed as a prompt to the user. The input provided by the user is returned as a string and can be stored in a variable.

Example:

hostIP = input("Device IP address: ")

In this example,"Device IP address: "is the prompt displayed to the user, and the user's input will be stored in the variablehostIP.

Options B, C, and D are syntactically incorrect in Python.

Python Official Documentation: Describes the use of theinput()function for getting user input.

Python Tutorials: Various tutorials demonstrate how to properly use theinput()function in scripts.

References:

A commit script in Junos is used to enforce policies and configuration constraints on the device. These scripts are written in Extensible Stylesheet Language Transformations (XSLT) or Python and are executed automatically during the commit process of a configuration change.

In this context, to prevent the deletion of the SNMP configuration, a commit script is the appropriate choice. It can be designed to check the configuration changes being committed and reject any commit that attempts to delete or modify the SNMP configuration. This script essentially acts as a gatekeeper, ensuring that only allowable changes are committed to the device configuration.

Supporting References:

Juniper Networks Commit Scripts Documentation:The official Juniper documentation provides examples and use cases of commit scripts, including how they can be used to prevent unauthorized changes to the device configuration.

"Junos Automation Scripting"by Jonathan Looney: This resource gives practical examples and best practices for creating commit scripts to enforce configuration policies in Junos OS.

XML Schema Definition (XSD) files are used to define the structure and data types of an XML document. They ensure that the XML document adheres to a specific structure by defining the allowed elements, attributes, and their data types, thereby enforcing a consistent format.

Option Ais correct because XSD files define the elements, attributes, and structure (hierarchy) of an XML document.

Option Dis correct because XSD files provide a standardized format, ensuring that all parties working with the XML document use the same set of tags and structure.

Option B (Every XML document must have an XSD file defined for it)is incorrect; not every XML document requires an XSD file, although it's beneficial for validation.

Option C (An XSD file is not an XML document)is incorrect because XSD files themselves are written in XML.

Supporting References:

W3C XML Schema Definition (XSD) Documentation:Explains the purpose and structure of XSD files, including their role in defining XML document schemas.

NETCONF (Network Configuration Protocol) is used for network device management and can operate over SSH. The following are true about NETCONF:

Default Port 830 (B): By default, NETCONF uses port 830 for communication over SSH. This is the standard port reserved for NETCONF sessions.

Use of Default SSH Port (D): NETCONF can also operate over the standard SSH port (port 22) if configured to do so. This allows flexibility in network management scenarios where port 830 might not be available or used.

Options A and C are incorrectbecause they refer to incorrect or non-applicable port numbers for NETCONF.

IETF RFC 6241: Specifies the use of NETCONF over SSH, including port details.

Juniper Networks NETCONF Documentation: Discusses the configuration and operation of NETCONF on Junos devices, including port usage.

References:

Python lists have the following characteristics:

Modifiable Data (A): Lists are mutable, meaning you can change, add, or remove elements after the list has been created.

Sequenced and Indexed (B): Lists maintain the order of their elements and are indexed starting from 0. This means you can access elements by their position in the list.

Option C is incorrectbecause lists are mutable, allowing modifications.Option D is incorrectbecause lists are indeed sequenced and indexed, unlike dictionaries.

Python Official Documentation: Covers the properties of lists, including mutability and indexing.

Python Data Structures Guide: Explains list operations and how to manipulate them.

References:

In Python, the==operator is used to test whether two variables are equal. It returnsTrueif the variables are equal andFalseif they are not.

Option B (==)is correct because it is the equality operator in Python.

Option A (!=)is used for inequality,Option C (%)is the modulus operator, andOption D (=)is used for assignment, not for testing equality.

Supporting References:

Python Documentation on Operators:The official Python documentation covers the use of==for equality checks.

In Junos, theJET (Junos Extension Toolkit)API supports direct modification of theEphemeral database. The Ephemeral database is a temporary configuration database used in Junos OS, allowing for changes that do not persist after a reboot unless explicitly committed to the permanent configuration.

JET API: Allows for high-performance interactions with Junos, including the ability to make changes to the Ephemeral database, which is useful for temporary configurations, dynamic policies, and other operational tasks.

Other options like WebSocket, SOAP, and REST do not provide direct access to the Ephemeral database in Junos.

Juniper Networks JET Documentation: Details how JET API interacts with the Ephemeral database.

Junos Automation and DevOps Documentation: Discusses the use of JET for automation and dynamic configuration.

References:

In Python, to use a package or module, you use theimportstatement. This statement allows you to load a module into your script so that you can use its functions, classes, and variables. For example, if you wanted to use themathmodule, you would writeimport math. This makes all the functions and constants in themathmodule available for use in your program.

Option A (reap), B (dir), and C (input)do not serve the purpose of importing modules.diris used to list the attributes of an object,inputis used to get user input, andreapis not a valid Python command related to importing modules.

Supporting References:

Python Documentation on Imports:The Python documentation provides clear guidelines on how to use theimportstatement to include modules in your Python scripts.