JNCIA-DevOps Data Serialization Practice Test 4 — 15 Questions

Question 1

You are writing a Python automation script that processes configuration data. The script reads a YAML file containing Junos firewall filters, modifies them, and writes them back out. However, you notice that all the original comments in the file are stripped out in the output. What is the fundamental reason for this behavior in standard PyYAML dump operations?

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

Accepted Answer

Comments are stripped during parsing because they are not part of the YAML data model.. PyYAML parses YAML files into abstract syntax trees (AST) or Python native data structures, discarding comments during the parsing phase because comments are not part of the data model.

Answer

The yaml.safe_dump() function explicitly deletes comments for security reasons.

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YAML specification mandates that all comments are ephemeral and cannot be serialized.

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Comments must be re-injected using the 'preserve_comments=True' parameter.

Question 2

Which TWO of the following are valid extensions commonly used for YAML files? (Choose two)

Accepted Answer

.yaml. YAML files commonly use either .yaml or .yml file extensions.

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.xml

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.jsn

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.txt

Question 3

Which TWO methods are provided by the Python standard library 'json' module for deserializing JSON data? (Choose two)

Accepted Answer

json.loads(). The json module provides json.load() for file-like objects and json.loads() for strings.

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json.read()

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json.decode()

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json.parse()

Question 4

When working with PyYAML in Python for Junos automation scripts, which THREE of the following practices enhance script security and robustness? (Choose three)

Accepted Answer

Always using yaml.safe_load() instead of yaml.load() to prevent arbitrary code execution.. Using safe loading methods, verifying file existence, and handling scanner errors properly are best practices when processing external YAML configurations.

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Storing unencrypted credentials directly inside YAML global anchors.

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Relying on yaml.load() to automatically execute embedded Python object constructors.

Question 5

Which TWO features are supported by YAML but are notably absent in standard JSON? (Choose two)

Accepted Answer

Anchors and aliases for data reuse within the document.. YAML supports comments and anchors/aliases, whereas standard JSON supports neither.

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Native browser execution support without parsing libraries.

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Strict enforcement of double quotes on all string keys.

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Strict indentation-based block scoping.

Question 6

When serializing Python data structures to JSON for Junos automation payloads, which THREE parameters can be passed to json.dumps() to control formatting and readability? (Choose three)

Accepted Answer

separators. Parameters like indent, sort_keys, and separators are standard formatting arguments for json.dumps().

Answer

max_depth

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strict_mode

Question 7

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

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Sequence

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Block

Question 8

Which TWO Python standard library modules are commonly combined when a script needs to fetch web content (such as Junos REST API data) and parse the resulting payload? (Choose two)

Accepted Answer

json. The 'urllib.request' module handles HTTP requests, and the 'json' module handles parsing the resulting JSON response.

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yaml

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socket

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pickle

Question 9

Which TWO characters or sequences are valid in YAML for representing lists or sequences? (Choose two)

Accepted Answer

Hyphen followed by a space (- ). YAML sequences can be represented using block style with hyphens (-) or flow style with square brackets ([]).

Answer

Semicolon followed by a space (; )

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Angle brackets (< >)

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Curly braces ({ })

Question 10

When serializing complex nested Python dictionaries to JSON, which THREE data types will cause a TypeError unless handled by a custom default encoder function? (Choose three)

Accepted Answer

Python set objects. Standard json.dumps() cannot serialize sets, complex numbers, or custom class instances without custom encoder logic.

Answer

Standard string objects

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Boolean values

Question 11

When writing an automation script that converts data formats between YAML and JSON for Junos configuration pipelines, which THREE potential pitfalls should an engineer account for? (Choose three)

Accepted Answer

JSON integer keys are automatically converted to strings in Python dictionaries.. Data type coercion differences (like booleans/octals), lack of comment preservation in JSON, and duplicate key behaviors are common conversion hurdles.

Answer

YAML automatically guarantees lossless round-trip conversion for all Python objects.

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JSON files natively support YAML anchors and aliases.

Question 12

Which TWO Python exceptions might be raised when attempting to parse a malformed JSON string using the standard 'json' module? (Choose two)

Accepted Answer

JSONDecodeError. json.loads() raises JSONDecodeError (which inherits from ValueError) when encountering invalid JSON syntax.

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AttributeError

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KeyError

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ScannerError

Question 13

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 JSON structure for easier manipulation in a web application. Which built-in Python module is primarily used to handle JSON data serialization and deserialization?

Accepted Answer

json. The 'json' module is the standard built-in Python library used for parsing, serializing, and deserializing JSON data.

Answer

pickle

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yaml

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xml.etree

Question 14

An engineer receives a YAML configuration snippet for a PyEZ automation script, but the script fails with a parser error. Upon inspection, the error is caused by improper indentation levels. Which rule must be strictly followed regarding indentation in YAML syntax?

Accepted Answer

Spaces must be used for indentation, and tabs are strictly forbidden.. YAML requires the use of space characters for indentation. Tab characters are strictly forbidden for indentation purposes.

Answer

Indentation is completely optional if curly braces are used.

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Tabs must be used consistently for every level of indentation.

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Indentation must always be exactly four spaces per level.

Question 15

You are writing a Python script using the PyEZ library to retrieve interface facts from a Juniper EX Series switch. The resulting data structure is stored in a Python dictionary. You need to dump this dictionary into a YAML file so it can be read by an Ansible playbook later. Which PyYAML function should you use to convert the Python dictionary into a YAML-formatted string or file stream?

Accepted Answer

yaml.dump(). yaml.dump() is the standard PyYAML function used to serialize Python objects (such as dictionaries) into a YAML-formatted stream or string.

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yaml.load()

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yaml.serialize()

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yaml.safe_load()