JNCIA-DevOps Data Serialization — 10 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?

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

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