JNCIA-DevOps Practice Test 4 — 25 Questions

Question 1

Which TWO commands or tools are associated with running JSNAPy snapshot verifications from a CLI environment? (Choose two)

Accepted Answer

jsnapy --snap. JSNAPy execution is invoked via command line tool 'jsnapy'.

Answer

pyez-snap --run

Answer

junos-snapshot --verify

Answer

juniper-snapshot-admin --test

Question 2

When working with the PyEZ Config utility, which THREE actions can be performed using the configuration context manager or its methods? (Choose three)

Accepted Answer

cu.validate(). The Config utility supports locking, loading configurations from various sources, validating, and rolling back.

Answer

cu.gather_facts()

Answer

cu.upgrade_os()

Question 3

An automation script needs to check if a Junos device supports a specific feature before executing an RPC. Which PyEZ property can be checked to inspect the software version loaded on the device?

Accepted Answer

dev.facts['version']. dev.facts['version'] holds the Junos OS version string.

Answer

dev.get_version()

Answer

dev.version

Answer

dev.os_version

Question 4

Which TWO methods are valid for loading configuration data into the PyEZ Config utility from different sources? (Choose two)

Accepted Answer

cu.load(text='set system hostname router1', format='set'). Config.load supports string data, file paths, and template rendering results.

Answer

cu.load(template_file='config.j2', engine='jinja2')

Answer

cu.load(database='active')

Answer

cu.load(action='commit')

Question 5

An automation script needs to compare pre- and post-change states on a Junos device using JSNAPy (Junos Snapshot Administrator). Which configuration file format is used by JSNAPy to define snapshot checks and test assertions?

Accepted Answer

YAML. JSNAPy uses YAML configuration files to define which RPC commands to run and what expected values or expressions should be evaluated against the resulting snapshots.

Answer

XML

Answer

JSON

Answer

INI

Question 6

You are writing a script that performs multiple configuration changes inside a single PyEZ Config context. How can you verify that the candidate configuration has syntax errors before committing it?

Accepted Answer

cu.validate(). The .validate() method checks the candidate configuration for syntax and semantic errors without committing.

Answer

cu.test_syntax()

Answer

cu.verify()

Answer

cu.check()

Question 7

When using Jinja2 inheritance, which tag is placed in a base template to indicate where child templates can insert their custom content?

Accepted Answer

{% block block_name %} ... {% endblock %}. The block tag defines regions that child templates can override.

Answer

Answer

{% insert block_name %}

Answer

{% child_content %}

Question 8

Which of the following data types is natively supported in JSON without requiring custom serialization handlers?

Accepted Answer

Boolean. JSON natively supports strings, numbers, booleans, null, arrays, and objects (dictionaries with string keys). Python tuples or sets are not natively supported.

Answer

Python set

Answer

Complex number

Answer

Python tuple

Question 9

An automation engineer is writing a Python script to parse a Juniper Junos NETCONF reply received in XML format and needs to convert it into a native Python dictionary for internal processing. Which built-in library should the engineer use to convert the structured XML tree?

Accepted Answer

xml.etree.ElementTree. xml.etree.ElementTree is a standard Python library used for parsing and navigating XML data structures. While JSON and YAML are common serialization formats, NETCONF protocol responses natively return XML, which must be parsed before data manipulation.

Answer

pickle

Answer

yaml

Answer

json

Question 10

An automation engineer is writing a Python script that takes a complex nested Python dictionary containing Junos telemetry parameters and converts it into a YAML string. Which PyYAML function should be used?

Accepted Answer

yaml.safe_dump(). yaml.safe_dump() converts a Python object into a YAML-formatted string safely, avoiding the security risks associated with the base yaml.dump().

Answer

yaml.export()

Answer

yaml.serialize_string()

Answer

yaml.to_yaml()

Question 11

You are writing a Python script that parses a multi-document YAML stream containing Junos device site configurations. One of the documents contains a custom YAML tag. When parsing with yaml.safe_load_all(), how does the safe loader handle custom tags?

Accepted Answer

It raises a ConstructorError unless a custom constructor is registered.. The safe loader in PyYAML does not know how to construct objects from custom tags by default and will raise a ConstructorError unless a custom constructor has been explicitly registered.

Answer

It converts the tagged object into a JSON equivalent.

Answer

It automatically evaluates the custom tag using Python eval().

Answer

It ignores the tag and loads the scalar value as a plain string.

Question 12

An automation script reads a multi-document YAML file containing configuration templates for various Junos router models. To process each document individually in Python using PyYAML, which function should the engineer invoke?

Accepted Answer

yaml.safe_load_all(). yaml.safe_load_all() is designed to parse a stream containing multiple YAML documents separated by '---', returning a generator that yields each parsed document sequentially.

Answer

yaml.read_multi()

Answer

yaml.load_all()

Answer

yaml.parse_documents()

Question 13

Which of the following characters is used to start a comment line in a YAML document?

Accepted Answer

Hash sign (#). Comments in YAML begin with the hash or pound sign (#) and continue to the end of the line.

Answer

Exclamation mark (!)

Answer

Percent sign (%)

Answer

Double forward slash (//)

Question 14

An automation engineer is reviewing data serialization formats used within Junos automation workflows. Which TWO statements are correct regarding JSON syntax and data types? (Choose two)

Accepted Answer

JSON object keys must be enclosed in double quotes.. JSON object keys must always be double-quoted strings, and null is a valid scalar value representing an empty or missing value.

Answer

Single quotes can be used interchangeably with double quotes for strings.

Answer

JSON supports inline comments starting with the '#' symbol.

Answer

Trailing commas are permitted in both arrays and objects.

Question 15

An automation engineer wants to log structured data from a Junos device automation run. The Python script formats a dictionary into a JSON string and prints it. However, the engineer wants all keys sorted alphabetically to ensure consistent log diffing. Which parameter accomplishes this in json.dumps()?

Accepted Answer

sort_keys=True. The sort_keys parameter in json.dumps() sorts the output of dictionaries by key alphabetically.

Answer

keys_sort=True

Answer

alphabetize=True

Answer

order='alphabetical'

Question 16

An automation scripter needs to load a YAML configuration file in Python. To prevent arbitrary code execution vulnerabilities associated with untrusted files, which function should always be called?

Accepted Answer

yaml.safe_load(). yaml.safe_load() restricts loading to simple Python types like scalars, lists, and dicts, preventing instantiation of arbitrary Python objects.

Answer

yaml.load()

Answer

yaml.secure_load()

Answer

yaml.restricted_load()

Question 17

An automation engineer is writing a script that saves operational telemetry data gathered from a Junos router. The data needs to be written directly to an open file stream in JSON format. Which method from the Python 'json' module should be used?

Accepted Answer

json.dump(). json.dump() takes a Python object and writes it directly to a file-like stream object, whereas json.dumps() returns a string.

Answer

json.dumps()

Answer

json.to_file()

Answer

json.write()

Question 18

Which Python module is part of the standard library and provides functions to serialize and deserialize JSON data?

Accepted Answer

json. The 'json' module is part of the Python standard library and requires no external installation.

Answer

requests

Answer

yaml

Answer

junos-eznc

Question 19

Which TWO of the following are valid scalar values in a YAML document? (Choose two)

Accepted Answer

Integer. Scalars in YAML represent single values like strings and integers.

Answer

Mapping

Answer

Sequence

Answer

Block

Question 20

What type of brackets enclose an array in a JSON document?

Accepted Answer

Square brackets ([ ]). Arrays in JSON are enclosed within square brackets ([ and ]).

Answer

Curly braces ({ })

Answer

Angle brackets (< >)

Answer

Parentheses (( ))