JNCIA-DevOps Data Serialization Practice Test 2 — 15 Questions

Question 1

A Python script reads a Junos configuration snippet stored in YAML. The configuration uses YAML anchors and aliases to duplicate common routing policy definitions across multiple VRFs. When the script parses the file using yaml.safe_load(), what happens to the anchors and aliases?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

The parser resolves the anchors and populates the resulting Python dictionary with the referenced data.. yaml.safe_load() fully supports YAML anchors (&) and aliases (*) by default, dereferencing them into identical Python data structures in memory.

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The parser raises a ScannerError because anchors are prohibited in safe mode.

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The aliases are ignored, resulting in empty values for those configuration blocks.

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The parser treats the anchor syntax as literal string data.

Question 2

What is the primary delimiter used to separate key-value pairs in a JSON object?

Accepted Answer

Comma (,). JSON object key-value pairs are separated by commas (,).

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Forward slash (/)

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Semicolon (;)

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Period (.)

Question 3

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.

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keys_sort=True

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alphabetize=True

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order='alphabetical'

Question 4

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

Accepted Answer

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

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Curly braces ({ })

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Angle brackets (< >)

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Parentheses (( ))

Question 5

A Python script processes a YAML configuration template for Junos BGP neighbors. The configuration contains a multi-line banner string description. Which YAML block scalar indicator preserves newlines exactly as written in the text block?

Accepted Answer

The pipe symbol (|). In YAML, the pipe symbol (|) denotes a literal scalar style, which preserves newlines within multi-line strings.

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The ampersand symbol (&)

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The greater-than symbol (>)

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The asterisk symbol (*)

Question 6

An automation engineer writes a Python script that reads a Junos configuration file serialized in JSON. The file opens successfully, but parsing fails with a JSONDecodeError due to trailing commas at the end of object lists. How does standard JSON handle trailing commas compared to YAML?

Accepted Answer

JSON strictly forbids trailing commas, whereas YAML permits them in collections.. Standard JSON strictly prohibits trailing commas in objects and arrays, whereas YAML is much more lenient and allows trailing commas in sequences and mappings.

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Both formats handle trailing commas identically by ignoring them.

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JSON allows trailing commas, but YAML strictly forbids them.

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Both JSON and YAML strictly require trailing commas for every key.

Question 7

When writing a Python script to interact with a Junos device via PyEZ, you receive an object representing RPC output. You want to serialize a custom Python class instance containing device metadata into JSON, but calling json.dumps() raises a TypeError. What is the standard approach to resolve this?

Accepted Answer

Pass a custom serialization function to the 'default' parameter in json.dumps().. The json module does not know how to serialize custom Python object instances by default. You must provide a custom serialization function and pass it to the 'default' parameter of json.dumps().

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Use yaml.safe_dump() instead, which natively serializes all custom Python classes.

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Convert the object into an XML string before calling json.dumps().

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Modify the global sys.path variable to include the custom class definition.

Question 8

An automation script reads a configuration template where boolean values are represented as 'yes' and 'no' in YAML. When parsed using PyYAML in Python, how are these values interpreted?

Accepted Answer

They are interpreted as Python boolean True and False values.. In YAML 1.1 (which PyYAML predominantly implements), unquoted words like 'yes', 'no', 'true', 'false', 'on', and 'off' are automatically parsed into native boolean values.

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They are converted to integer 1 and 0 values.

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They remain as literal string objects ('yes' and 'no').

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The parser raises a ConstructorError because only 'true' and 'false' are valid.

Question 9

You are writing a Python automation script that reads a Junos configuration file in JSON format. The JSON file contains duplicate keys within the same object scope. According to the JSON specification RFC 8259, how should a conforming JSON parser handle duplicate keys?

Accepted Answer

Behavior is undefined by the specification; typically the last defined key-value pair overwrites previous ones in Python dictionaries.. RFC 8259 states that while names within an object SHOULD be unique, the specification does not mandate how parsers should handle duplicates, resulting in behavior dependent on the parser (typically keeping the last encountered key-value pair).

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Both values are automatically combined into a JSON array under that key.

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Duplicate keys are prohibited, and compliance checks will reject the file pre-parsing.

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The parser must raise a fatal JSONDecodeError immediately.

Question 10

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.

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requests

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yaml

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junos-eznc

Question 11

Which symbol represents the beginning of a single YAML document stream?

Accepted Answer

Three dashes (---). YAML documents can optionally begin with a document start marker consisting of three dashes (---).

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Three hashes (###)

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Three slashes (///)

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Three dots (...)

Question 12

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.

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json.dumps()

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json.to_file()

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json.write()

Question 13

When parsing a Junos configuration snippet in YAML, an engineer notices a string value starting with a zero (e.g., '01234') that is unquoted. How do YAML parsers typically interpret this value?

Accepted Answer

As an octal integer.. In YAML 1.1, numbers starting with a leading zero are interpreted as octal (base 8) integers. To ensure it is treated as a string, it must be quoted.

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The parser throws a ScannerError due to invalid numeric formatting.

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As a string literal matching the exact characters.

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As a floating-point number with zero prefix.

Question 14

An engineer needs to convert an existing YAML-formatted inventory file into JSON format using a Python script. Which workflow accomplishes this transformation?

Accepted Answer

Load YAML with yaml.safe_load() and serialize to JSON with json.dumps().. To convert YAML to JSON, the engineer must read and parse the YAML file into a Python data structure using yaml.safe_load(), and then serialize that structure into a JSON string using json.dumps().

Answer

Directly pass the YAML file object into json.load().

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Rename the file extension from .yaml to .json.

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Use yaml.safe_dump() directly on the JSON output stream.

Question 15

You are writing a Python automation tool that reads telemetry data from a Junos device. The data is received as a JSON string containing forward slashes escaped as '\/'. When you load this string using json.loads(), how does Python handle the escaped slashes?

Accepted Answer

They are automatically converted to unescaped forward slashes ('/').. JSON allows forward slashes to be escaped as '\/' for embedding JSON inside HTML script tags. Python's json.loads() automatically unescapes '\/' into normal '/' characters in the resulting string.

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The parser raises a ValueError because escaped slashes are invalid in JSON.

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They remain as literal escaped sequences ('\/').

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They are converted to backslashes ('\').