JNCIA-DevOps Practice Exam 3 — 20 Questions

Question 1

When using the Junos REST API to configure static routes, how does the JSON payload structure represent list items that can have multiple instances (such as multiple next-hops or static routes)?

Accepted Answer

As JSON arrays containing objects for each list entry.. In Junos REST API JSON representations, multi-instance configuration lists are typically represented as arrays of JSON objects.

Answer

As XML CDATA blocks embedded within JSON keys.

Answer

As numerical indexed keys (e.g., 'route-0', 'route-1').

Answer

As a single concatenated string separated by semicolons.

Question 2

You are building a custom PyEZ application and need to catch exceptions specific to configuration parsing failures returned by Junos. Which exception class should your script import?

Accepted Answer

from jnpr.junos.exception import ConfigError. ConfigError is raised by PyEZ when configuration loading or committing fails.

Answer

from jnpr.junos.device import ConfigurationFailed

Answer

from jnpr.junos.utils.config import ConfigError

Answer

from jnpr.junos.exception import ParseError

Question 3

Which THREE features are provided by the Junos REST API daemon (jpagent) when running on a Junos device? (Choose three)

Accepted Answer

Translation between REST requests/JSON/XML payloads and Junos configuration/operational structures.. The jpagent daemon provides HTTP/HTTPS server capabilities, authentication handling against local/AAA databases, and translation between HTTP requests/JSON/XML and Junos internal RPC/configuration structures.

Answer

Kernel-level packet forwarding optimization for ASIC line cards.

Answer

Autonomous BGP route reflection across core routing instances.

Question 4

What is the primary benefit of using PyEZ Table and View abstractions over raw RPC XML parsing in Python scripts?

Accepted Answer

They automatically convert XML into structured Python data structures like dictionaries and lists. Tables and Views abstract complex XML trees into clean Python dictionaries and lists.

Answer

They eliminate the need to establish a Device connection object

Answer

They allow direct execution of Junos CLI operational commands without NETCONF

Answer

They automatically commit configurations to the active database

Question 5

Which statement correctly identifies the relationship between Junos REST API and NETCONF data models?

Accepted Answer

Both protocols leverage the same underlying Junos data models and management infrastructure.. Both the Junos REST API and NETCONF interface with the same underlying Junos YANG data models and management infrastructure (MGD), providing different transport and encoding wrappers for the same capabilities.

Answer

REST API bypasses all Junos data models and writes directly to kernel memory.

Answer

NETCONF uses YANG models, whereas REST API uses proprietary relational databases.

Answer

NETCONF is deprecated in favor of REST API for all Junos configuration tasks.

Question 6

When configuring advanced options for the Junos REST API jpagent, which THREE parameters or sub-statements can be configured under the 'set system services jpagent' hierarchy? (Choose three)

Accepted Answer

traceoptions. Under 'set system services jpagent', administrators can configure HTTPS, custom HTTP/HTTPS ports, and connection timeouts or limits depending on Junos software version support.

Answer

bgp-peer-group

Answer

ethernet-switching

Question 7

Which TWO statements are true regarding PyEZ Table and View definitions? (Choose two)

Accepted Answer

A View defines how individual fields within the returned XML elements are mapped to Python dictionary keys.. Tables map to RPCs and Views map to item fields using YAML.

Answer

Tables can only be used to modify device configurations, not read operational state.

Answer

Tables require Jinja2 templates to parse raw XML output.

Answer

Views replace the need to instantiate a Device object.

Question 8

An automation developer is writing a script to modify candidate configuration data on a Junos device using the REST API. Which HTTP method and request body format should be used to replace an existing configuration hierarchy?

Accepted Answer

PUT method with a JSON or XML payload representing the configuration node. To modify or replace configuration data, the PUT method is typically used in the Junos REST API configuration endpoints with JSON or XML payload.

Answer

POST method with form-urlencoded data

Answer

DELETE method with an empty body

Answer

GET method with URL parameters

Question 9

Which statement accurately describes how the Junos REST API handles configuration locking compared to NETCONF workflows?

Accepted Answer

NETCONF requires explicit lock commands, whereas the Junos REST API handles configuration locking implicitly during API-driven edit sessions.. While NETCONF explicitly supports lock and unlock protocol operations, the Junos REST API manages configuration locks implicitly or through explicit session management parameters during commit operations.

Answer

NETCONF does not support configuration locking at all.

Answer

The Junos REST API uses exclusive database locking for every GET request.

Answer

The Junos REST API requires manual SSH tunnel establishment before locks can be applied.

Question 10

Which NETCONF capability URI indicates that the server supports rolling back configuration changes to previous commit points?

Accepted Answer

Juniper specific capability strings for commit/rollback features advertised in the hello banner.. Junos supports rollback capabilities advertised via specific NETCONF capability URIs.

Answer

urn:ietf:params:netconf:capability:rollback-on-error:1.0

Answer

http://xml.juniper.net/netconf/junos/1.0

Answer

urn:ietf:params:netconf:base:1.0

Question 11

An engineer is applying a candidate configuration using PyEZ and needs to load it from an external text file named 'interfaces.conf'. Which Config method should be used?

Accepted Answer

cu.load(path='interfaces.conf', format='text'). The load method with path and format parameters is used to load configuration text from a file.

Answer

dev.load_configuration(file='interfaces.conf')

Answer

cu.load_file('interfaces.conf')

Answer

cu.read_config('interfaces.conf')

Question 12

What is the primary templating engine used alongside Python for generating structured Junos configuration text in network automation workflows?

Accepted Answer

Jinja2. Jinja2 is the standard Python templating engine used for rendering configuration templates.

Answer

Ansible Engine

Answer

Mako

Answer

ERB

Question 13

An automation engineer is writing an application that sends an RPC to a Junos device to load a replacement configuration. The requirement is to completely replace the candidate configuration with the provided configuration content. Which element and attribute combination should be used inside the request?

Accepted Answer

replace. To replace the entire configuration or a specific hierarchy level, the element can be set to 'replace', or the element itself can carry the operation='replace' attribute.

Answer

<load-options>replace</load-options>

Answer

replace-all

Answer

<action>overwrite</action>

Question 14

Which TWO statements are true regarding the NETCONF protocol hello message exchange? (Choose two.)

Accepted Answer

Both client and server exchange capabilities using XML elements containing URI strings.. During the initial NETCONF hello message exchange, both the client and server advertise their supported capabilities using URIs, and the session ID is assigned by the server.

Answer

The client uses the hello message to lock the configuration database before session initialization.

Answer

The client hello message must include the list of YANG modules it intends to modify during the session.

Answer

The hello message exchange is optional if a pre-shared SSH key is used for authentication.

Question 15

You are writing a Python script to gather operational state information from a Junos device using PyEZ. Which method should you call on an open Device instance to retrieve standard hardware and OS inventory facts into a dictionary?

Accepted Answer

dev.facts. The .facts method populates a dictionary with system inventory details such as model, serial number, and version.

Answer

dev.rpc.get_system_inventory()

Answer

dev.gather_facts()

Answer

dev.get_facts()

Question 16

In a Jinja2 template designed for Junos configuration, how do you correctly output the value of a variable named 'hostname'?

Accepted Answer

{{ hostname }}. Jinja2 uses double curly braces to print or evaluate variables.

Answer

${hostname}

Answer

{% hostname %}

Answer

<< hostname >>

Question 17

In a Python script utilizing PyEZ, what method must be called on the Device instance after all configuration and operational tasks are complete to properly terminate the NETCONF session?

Accepted Answer

dev.close(). The .close() method terminates the NETCONF session cleanly.

Answer

dev.terminate()

Answer

dev.end_session()

Answer

dev.disconnect()

Question 18

You have captured a baseline snapshot using JSNAPy and want to compare a newly taken snapshot against that baseline. Which JSNAPy command-line action executes this comparison?

Accepted Answer

jsnapy --check. The check action compares current operational state against a snapshot baseline.

Answer

jsnapy --test

Answer

jsnapy --verify

Answer

jsnapy --compare

Question 19

When writing Jinja2 templates for Junos configurations, which THREE control flow or filtering constructs are valid? (Choose three)

Accepted Answer

{% for vlan in vlans %} ... {% endfor %}. Jinja2 supports filters, loops, and conditional statements.

Answer

[# foreach item in list #] ... [# endfor #]

Answer

<< if interface_active >> ... << endif >>

Question 20

You are writing a script that uses Jinja2 to dynamically render a Junos interface configuration. Which Python module and function are required to load a template from the local filesystem and render it with a dictionary of variables?

Accepted Answer

from jinja2 import Environment, FileSystemLoader. Jinja2 utilizes a FileSystemLoader to find templates on disk and an Environment to manage them, allowing you to get_template() and render() with context variables.

Answer

from jnpr.junos.cfg import ConfigTemplate

Answer

from jnpr.junos.template import TemplateRenderer

Answer

import jnpr.junos.utils.jinja as jinja