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

In Python, lists are zero-indexed, meaning the first element of the list is at index 0. The given script is:

pythona = [1, 2, 3, 4, 5, 6, 7, 8, 9]

print(a[0])

a[0]refers to the first element in the lista, which is1.

So, the output of theprint(a[0])command is1.

Option A is correct because Python indexing starts at 0, making the first element of the list at index 0.

Python Official Documentation: Covers list indexing and operations.

Python Programming Tutorials: Provide examples of list indexing.

References:

QUESTION NO: 64

Which statement is correct about Ansible playbooks?

A. A playbook is a configuration file that defines the Ansible related parameters

B. A playbook contains one or more tasks written in XML

C. A playbook can contain multiple tasks and execute multiple Python modules

D. A playbook is a specific Python module that is executed on a host

Answer:C

 A. It supports data in CSV format:The Junos REST API supports multiple data formats for transferring information between systems, including XML, JSON, andCSV (Comma Separated Values). This flexibility allows for easier data parsing, especially in environments where structured data (likeCSV) is a standard. CSV is often used for bulk data export or import and reporting purposes, making it an essential format for automation tasks involving external systems or large datasets.

Example Usage in REST API:When using the Junos REST API, a user can request configuration or operational data and specify the response format (XML, JSON, or CSV). CSV is particularly useful when integrating Junos devices with systems that require easily readable, tabular formats.

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:

In Python, to create a list, you use square brackets[]. The correct syntax to create a list containing the numbers 0 through 5 is:

L = [0, 1, 2, 3, 4, 5]

This statement creates a list object that stores the specified integers.

Other options are incorrect:

Adefines a string, not a list.

Bdefines a set, which is an unordered collection with no duplicate elements.

Ddefines a tuple, which is an immutable sequence, not a list.

Python Official Documentation: Discusses lists, sets, tuples, and their syntaxes.

Python Data Structures Guide: Provides examples of creating and manipulating lists.

References:

The NETCONF protocol, used for network management, utilizes XML for encoding the RPC (Remote Procedure Call) requests and responses. XML is chosen because of its flexibility and ability to represent hierarchical data structures, making it well-suited for representing network configurations and states.

Option Bis correct because XML is the standard format used for NETCONF RPC payloads.

Options A (YAML), C (JSON), and D (HTML)are incorrect because these formats are not used by NETCONF for its RPC payloads.

Supporting References:

RFC 6241 - NETCONF Protocol:This RFC describes the use of XML for encoding NETCONF messages.

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:

Python follows a specific execution flow when a script is run:

The code is interpreted:Python is an interpreted language, meaning that the Python interpreter reads the code line by line. When a Python script is executed, the interpreter first reads the source code.

The code is translated to bytecode:After interpreting the source code, Python translates it intobytecode. Bytecode is an intermediate representation of the source code that is portable and efficient for execution by the Python Virtual Machine (PVM).

The bytecode is executed in runtime:Finally, thePython Virtual Machine (PVM)executes the bytecode. The PVM is a part of the Python runtime environment, responsible for interpreting the bytecode into machine-specific instructions for execution.

Hence, the correct sequence is:interpreted → translated to bytecode → bytecode executed in runtime.

Why the Other Options Are Incorrect:

Options A, C, and D present an incorrect order of the script execution process, especially in how bytecode is generated and executed.

References:

Python’s documentation on the interpreter and its execution model explains this standard process.

An XML schema document (XSD) is a key component in defining the structure and constraints of XML data used in various applications, including Junos:

Authoritative Source (C): An XML schema document serves as the authoritative definition of the structure, content, and semantics of XML documents. It ensures that the XML data adheres to specific rules and formats, which is essential for both operational and configuration XML.

XSD Format (D): XML schema documents are typically written in the XSD (XML Schema Definition) format, which provides a formal description of the XML document's structure.

Option A is incorrectbecause XML schemas are not formatted as XLT files (which are related to XSLT transformations), andOption B is incorrectbecause XML schemas can indeed be examined in the Junos CLI using appropriate commands.

W3C XML Schema Definition Language (XSD) Documentation: Provides comprehensive information on the XSD format.

Juniper Networks Documentation: Discusses the role of XML schemas in managing Junos configurations.

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.

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.

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