JNCIA-DevOps Practice Test 3 — 25 Questions

Question 1

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 2

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 3

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 4

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 5

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 6

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 7

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 8

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 9

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 10

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

Question 11

What Jinja2 feature allows you to include the contents of another template file into your main configuration template?

Accepted Answer

{% include 'filename.j2' %}. The {% include %} tag allows inserting another template's content.

Answer

{% insert 'filename.j2' %}

Answer

{% import 'filename.j2' %}

Answer

Question 12

Which THREE exceptions can be raised by PyEZ during script execution when interacting with a Junos device? (Choose three)

Accepted Answer

RpcError. PyEZ defines specific exceptions in jnpr.junos.exception for connection, configuration, and RPC errors.

Answer

DatabaseLockedError

Answer

TemplateRenderError

Question 13

You are using the PyEZ SW utility to install a new Junos image on a device. Which method parameter allows the script to automatically reboot the device after a successful installation?

Accepted Answer

reboot=True. The val parameter or reboot=True flag is typically used depending on the specific SW.upgrade() call signature. Specifically, reboot=True forces the reload.

Answer

auto_reboot=1

Answer

reload_after_install=True

Answer

action='reboot'

Question 14

When designing a custom PyEZ Table and View mapping in Python, what configuration parameter in the YAML definition file specifies the RPC or CLI command executed to gather the raw data?

Accepted Answer

rpc:. The 'rpc' or 'command' keyword in a PyEZ Table YAML definition specifies the underlying command to run.

Answer

get-rpc:

Answer

exec:

Answer

command_string:

Question 15

An automation engineer is writing a Python script using Junos PyEZ to connect to a device. Which module and class must be imported to instantiate a device object representing the Junos target?

Accepted Answer

from jnpr.junos.device import Device. The Device class from the jnpr.junos module is the foundational class used in PyEZ to manage connections and sessions with Junos devices.

Answer

from jnpr.junos.rpcs import RPC

Answer

from jnpr.junos.facts import Facts

Answer

from jnpr.junos.utils.sw import SW

Question 16

You are rendering a Jinja2 template in Python that includes a loop over a list of VLANs. Which Jinja2 block syntax correctly iterates over a list named 'vlan_list'?

Accepted Answer

{% for vlan in vlan_list %} ... {% endfor %}. Jinja2 uses {% for item in list %} ... {% endfor %} syntax for iteration.

Answer

{{ for vlan in vlan_list }} ... {{ endfor }}

Answer

[for vlan in vlan_list] ... [endfor]

Answer

<% for vlan in vlan_list %> ... <% endif %>

Question 17

When using Jinja2 templates in Python to generate configurations, how can you load a template file from disk prior to rendering it with variables?

Accepted Answer

Template(open('template.j2').read()). Environment and FileSystemLoader are used to load templates from a directory path.

Answer

template.open('template.j2')

Answer

import_template('template.j2')

Answer

jinja2.load_file('template.j2')

Question 18

When using PyEZ to push a configuration, you want to log out all NETCONF XML traffic exchanged between the script and the Junos device for debugging purposes. How do you enable this logging in Python?

Accepted Answer

Configuring Python logging for the 'jnpr.junos' logger with DEBUG level. Python's standard logging module configured for the jnpr.junos logger enables debug output.

Answer

import jnpr.junos.debug; jnpr.junos.debug.enable()

Answer

dev.rpc.trace(enabled=True)

Answer

dev.debug = True

Question 19

What is JSNAPy primarily used for in Junos network automation?

Accepted Answer

Taking operational state snapshots and verifying device health. JSNAPy (Junos Snapshot Administrator) is used to capture operational state snapshots of Junos devices and compare them to detect changes or anomalies.

Answer

Compiling Junos CLI operational commands into Python bytecode

Answer

Performing automated firmware upgrades across clusters

Answer

Generating static configuration templates

Question 20

You want to run a JSNAPy verification test via Python code. Which Python class should you import and instantiate to execute the snapshot comparison programmatically?

Accepted Answer

from jnpr.jsnapy import SnapAdmin. The JSNAPy class is imported from jnpr.jsnapy to execute snapshot checks programmatically.

Answer

from jnpr.jsnapy.verify import VerifyEngine

Answer

from jnpr.junos.utils.jsnapy import JSNAPy

Answer

from jnpr.jsnapy.runner import JSNAPyRunner