JNCIA-DevOps Data Serialization — Timed 20 Questions

Question 1

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?

20 minute time limit — choose an answer to begin.

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 2

An engineer needs to represent an ordered list of IP addresses in a YAML configuration file for a Junos automation playbook. Which valid YAML syntax correctly defines a sequence of items?

Accepted Answer

ip_addresses:
  - 192.168.1.1
  - 192.168.1.2. In YAML, lists or sequences are represented using a hyphen followed by a space (-) at the beginning of each line.

Answer

ip_addresses = {192.168.1.1, 192.168.1.2}

Answer

ip_addresses: [192.168.1.1: 192.168.1.2]

Answer

ip_addresses:
  * 192.168.1.1
  * 192.168.1.2

Question 3

A Python script retrieves interface statistics from a Junos device in JSON format, modifies a threshold value, and needs to output it back into a formatted JSON string with an indentation level of 4 spaces for readability. Which Python snippet achieves this?

Accepted Answer

json.dumps(data, indent=4). The json.dumps() method accepts an 'indent' parameter which specifies the number of spaces to use for pretty-printing the resulting JSON string.

Answer

json.format(data, spacing=4)

Answer

json.dump(data, indent=4)

Answer

json.stringify(data, spaces=4)

Question 4

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 5

A network automation script is reading a YAML configuration file containing Junos device credentials. The script encounters an unhandled exception when attempting to load the file using PyYAML. Upon inspection, the error is caused by a tab character used for indentation instead of spaces. Which YAML specification rule does this violate?

Accepted Answer

Tab characters are strictly forbidden for indentation in YAML.. YAML 1.2 specifications explicitly prohibit the use of the tab character for indentation. All indentation whitespace must consist exclusively of space characters to maintain hierarchy definition.

Answer

Comments must start with a double forward slash (//).

Answer

YAML files require all keys to be wrapped in double quotes.

Answer

Top-level keys must start with a hyphen (-) character.

Question 6

You are writing a Python automation script that processes JSON output from a Junos device's 'show interfaces' operational command via PyEZ. One of the interface descriptions contains raw control characters. When the script attempts to dump this data to a JSON string using json.dumps(), it raises a ValueError. Which parameter should you pass to json.dumps() to handle non-printable or out-of-range character encoding gracefully?

Accepted Answer

ensure_ascii=False. The json.dumps() function in Python includes an 'ensure_ascii' parameter. When set to False, it allows non-ASCII characters to be emitted directly without raising serialization errors or escaping them into Unicode escape sequences.

Answer

skipkeys=True

Answer

check_circular=False

Answer

allow_nan=True

Question 7

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 8

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 9

Which character is used to indicate a mapping key-value pair in YAML syntax?

Accepted Answer

Colon (:). In YAML, a key-value mapping is represented by a colon followed by a space (: ).

Answer

Semicolon (;)

Answer

Arrow (->)

Answer

Equals sign (=)

Question 10

Which file extension is conventionally used for YAML data serialization files?

Accepted Answer

.yaml. YAML files typically use .yaml or .yml extensions.

Answer

.json

Answer

.ini

Answer

.xml

Question 11

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 12

A Python script receives a JSON payload from a Junos device containing 64-bit interface counter integers. When loaded using the standard 'json' module, the script experiences precision loss on counter values exceeding standard integer limits. Which alternative JSON parser package for Python should be used to handle high-precision integers without data degradation?

Accepted Answer

simplejson with use_decimal=True. The 'ujson' (UltraJSON) or 'simplejson' libraries provide options like parse_float or parse_int to handle high-precision numbers. Specifically, simplejson supports a 'use_decimal=True' parameter to decode JSON numbers into Python Decimal objects.

Answer

corejson

Answer

xmljson

Answer

fastjson

Question 13

An automation engineer needs to convert a JSON payload representing Junos interface configurations into equivalent YAML format to reuse in an Ansible playbook. Which fundamental structural relationship between JSON and YAML makes this conversion straightforward?

Accepted Answer

YAML is a strict superset of JSON, allowing valid JSON to be parsed as YAML.. YAML is a superset of JSON, meaning any valid JSON document is technically also a valid YAML document, allowing direct mapping of data structures.

Answer

JSON uses indentation for structure just like YAML.

Answer

JSON and YAML both strictly require curly braces for all data containers.

Answer

YAML forces all numeric values to be encapsulated in strings.

Question 14

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 15

When converting a deeply nested JSON data structure representing Junos device health metrics into YAML using PyYAML, the output uses complex block styles that are difficult for team members to read. Which parameter in yaml.safe_dump() can force scalar values or containers to prefer flow style (JSON-like curly braces and brackets) instead?

Accepted Answer

default_flow_style=True. The default_flow_style parameter in yaml.safe_dump() controls how collections are dumped. Setting default_flow_style=False uses block style, while True or None dictates flow style formatting.

Answer

force_json=True

Answer

format='compact'

Answer

style='flow'

Question 16

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?

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.

Answer

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

Answer

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

Answer

The parser treats the anchor syntax as literal string data.

Question 17

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 (,).

Answer

Forward slash (/)

Answer

Semicolon (;)

Answer

Period (.)

Question 18

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 19

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 (( ))

Question 20

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.

Answer

The ampersand symbol (&)

Answer

The greater-than symbol (>)

Answer

The asterisk symbol (*)