JNCIA-DevOps Practice Test 2 — 10 Questions

Question 1

What is the primary benefit of using structured data formats (such as XML, JSON, or YAML) over unstructured CLI text output in Junos automation?

Accepted Answer

They allow automation scripts to parse device output reliably without relying on brittle regular expressions.. Structured data formats can be easily parsed programmatically without relying on fragile regular expressions.

Answer

Structured data formats take up less memory on the Junos Routing Engine hard drive.

Answer

They eliminate the need to authenticate when connecting via NETCONF or gRPC.

Answer

They automatically convert all IPv4 addresses to IPv6 format.

Question 2

You are using the PyEZ SW utility to install a new Junos image on a device. Which method parameter allows the script to automatically reboot the device after a successful installation?

Accepted Answer

reboot=True. The PyEZ SW utility's install() method accepts a reboot=True parameter that instructs the utility to reboot the device automatically after the Junos image is successfully installed. This is the documented keyword argument in the jnpr.junos.utils.sw.SW class, and it triggers the device reboot as part of the install workflow.

Answer

auto_reboot=1

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reload_after_install=True

Answer

action='reboot'

Question 3

You are developing a Python script using PyEZ to load a configuration onto a Junos device. You need to ensure that the configuration is merged with the existing candidate configuration, and that the load operation does not perform a commit check automatically. Which method should you use to load the configuration from a file?

Accepted Answer

Use `cu.load(path='config.conf', merge=True, check=False)`. The `load` method of the PyEZ `Config` object supports `merge` and `check` parameters. To merge without a commit check, use `merge=True` and `check=False`. The other options either use incorrect parameter names, perform an overwrite, or enable the check. Only the combination of merge and check=False achieves the desired behavior.

Answer

Use `cu.load(path='config.conf', overwrite=True, check=False)`

Answer

Use `cu.load(path='config.conf', merge=True, commit_check=True)`

Answer

Use `cu.load(path='config.conf', action='merge', verify=False)`

Question 4

What is the primary benefit of decoupling network configuration data (YAML/JSON) from presentation templates (Jinja2) in network automation?

Accepted Answer

It allows non-engineers to modify device variables without altering the core template logic, promoting the DRY principle.. Separating data from templates allows the same template to be reused across multiple devices with different data sets, adhering to DRY principles.

Answer

It eliminates the need for any version control system.

Answer

It converts all configuration files into binary format to save disk space.

Answer

It forces the Junos device to run all configuration commits in parallel across all line cards.

Question 5

An engineer needs to retrieve the entire candidate configuration in JSON format from a Junos device using the Junos REST API. Which HTTP header must be included in the GET request to ensure the response is returned in JSON format?

Accepted Answer

Accept: application/json. The Accept header with 'application/json' specifies that the client expects the response to be formatted in JSON.

Answer

Transfer-Encoding: chunked

Answer

Content-Type: text/xml

Answer

X-Junos-Data-Format: json

Question 6

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.

Answer

They are converted to integer 1 and 0 values.

Answer

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

Answer

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

Question 7

Which Junos automation toolset relies heavily on XML over NETCONF and provides robust Python libraries tailored specifically for Junos network devices?

Accepted Answer

Junos PyEZ. Junos PyEZ is the Python library tailored specifically for Junos devices using NETCONF.

Answer

Cisco IOS XE Embedded Event Manager (EEM)

Answer

Microsoft PowerShell Active Directory module

Answer

Arista eAPI Python client library

Question 8

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.. Option C is correct because JSON object keys are always strings, so when Python's json module loads a JSON document, any key that appears numeric (e.g., 1) becomes the string '1', which can break lookups or round-trips if the script expects an integer key. Option D is correct because JSON has no comment syntax, so any YAML comments (# ...) are discarded by the YAML parser and cannot be represented in the resulting JSON output. Option E is correct because YAML 1.1 parsers interpret unquoted scalars such as 'yes'/'no' as booleans and leading-zero values like 012 as octal integers, silently changing the data type unless the scalars are explicitly quoted. Option A is wrong because YAML does not guarantee lossless round-trip conversion for arbitrary Python objects (custom types, tuples, sets, etc. require tags or custom representers). Option B is wrong because JSON has no native support for YAML anchors and aliases; those are YAML-specific features that must be resolved before JSON serialization.

Answer

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

Answer

JSON files natively support YAML anchors and aliases.

Question 9

An automation engineer wants to retrieve information about all software packages installed on a Junos device using the REST API. Which operational RPC endpoint category is typically targeted?

Accepted Answer

/api/operational/rpc/get-software-information. The Junos REST API exposes operational RPCs under the /api/operational/rpc/ path, and software package information is retrieved via the get-software-information RPC. This endpoint returns details about installed packages, versions, and related state. The other options either target configuration hierarchies or use non-existent REST paths.

Answer

/api/configuration/system/software

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/netconf/rpc/software

Answer

/api/v1/packages/status

Question 10

Which TWO data serialization formats can an automation engineer request using the 'Accept' header in a Junos REST API GET request? (Choose two)

Accepted Answer

application/json. The Junos REST API supports content negotiation through the HTTP Accept header, and the two media types it recognizes for structured data responses are application/json (option C) and application/xml (option D); requesting either of these causes the device to return the RPC reply serialized in JSON or XML respectively. JSON is the default and most commonly used format for automation tooling, while XML mirrors the native Junos XML API output, so both are valid and correct. The remaining options are not supported by the Junos REST API: application/yaml (A) is not a media type Junos negotiates, text/csv (B) is not a serialization format the API emits, and application/octet-stream (E) denotes an opaque binary stream rather than a structured serialization format.

Answer

application/yaml

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text/csv

Answer

application/octet-stream