JNCIA-DevOps Practice Test 15 — 15 Questions

Question 1

An automation script attempts to unlock a candidate configuration datastore that was previously locked by a different NETCONF session. Which RPC is required to force-terminate that session and release the lock?

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

Accepted Answer

...

. The RPC allows terminating another active NETCONF session, which automatically releases any locks held by that session.

Answer

Answer

<release-lock session-id="..."/>

Answer

<close-session><session-id>...</session-id></close-session>

Question 2

While executing a NETCONF edit-config operation, you want to ensure that any syntax errors or invalid statements immediately cause the device to roll back the entire transaction without applying partial changes. Which parameter achieves this?

Accepted Answer

rollback-on-error. The error-option element with the value 'rollback-on-error' instructs the device to abort and roll back if any error occurs.

Answer

test-then-set

Answer

<default-operation>none</default-operation>

Answer

stop-on-error

Question 3

When modifying a Junos device configuration using the PyEZ Config table-driven or Context manager (with Config(dev) as cu:), what is the default behavior regarding locking the candidate configuration?

Accepted Answer

It automatically locks the candidate configuration upon entry and unlocks it upon exit.. When entering the Config context manager in PyEZ, it automatically locks the candidate configuration database to prevent concurrent edits and unlocks it upon exiting the context.

Answer

It locks the global database and forces all other users into maintenance mode.

Answer

It requires an explicit cu.lock() call before any load operation can take place.

Answer

It locks the running configuration and restarts the mgd daemon.

Question 4

Which TWO tasks are typically automated using Python and PyEZ in a network DevOps pipeline? (Choose two)

Accepted Answer

Automated pushing of validated Jinja2-generated configurations to candidate databases. Option C is correct because PyEZ (junos-eznc) provides modules such as Config and the load() method with merge/override/replace actions that push Jinja2-rendered configuration text into the candidate database, then commit it — a core use case in network DevOps pipelines for templated, validated config deployment. Option D is correct because PyEZ exposes operational RPCs via the RPC class and facts/table retrieval (e.g., get_interface_information, get_route_information), enabling scripts to run pre-checks before a change and post-checks after a maintenance window to verify state and automatically roll back on failure. Option A is not correct because PyEZ operates at the Junos management/RPC layer over NETCONF or the Junos XML API, not at Layer 1 physical media, where packet capture requires tools like tcpdump or dedicated analyzers. Option B is not correct because firmware assembly is a low-level hardware/vendor engineering task, not something PyEZ automates. Option E is not correct because compiling Junos kernel device drivers in C++ is part of Juniper's internal OS build process, not a PyEZ automation task.

Answer

Direct packet capture inspection at Layer 1 physical media levels

Answer

Writing device firmware assembly code

Answer

Compiling Junos kernel device drivers in C++

Question 5

Which of the following data types is natively supported in JSON without requiring custom serialization handlers?

Accepted Answer

Boolean. JSON natively supports a limited set of data types: string, number, boolean, null, array, and object. Boolean is one of these primitive types, so it can be directly represented as true or false without any custom serialization. This makes it straightforward to include boolean values in JSON payloads for APIs and configuration files.

Answer

Python set

Answer

Complex number

Answer

Python tuple

Question 6

An engineer executes a NETCONF <discard-changes> RPC. What is the precise effect of this operation on the Junos device?

Accepted Answer

It discards all uncommitted changes currently sitting in the candidate datastore, reverting it to match the running datastore.. The <discard-changes> RPC discards any uncommitted changes present in the candidate configuration datastore.

Answer

It clears all active alarms and operational logs from the routing engine.

Answer

It terminates all active NETCONF sessions currently connected to the device.

Answer

It reverts the active running configuration to the factory default state.

Question 7

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.. Option D is correct because YAML provides anchors (&) and aliases (*) that let you define a node once and reference it elsewhere in the same document, a reuse mechanism JSON lacks entirely. Option E is correct because YAML natively supports comments introduced by the hash (#) symbol, whereas standard JSON (per RFC 8259) defines no comment syntax at all. Option A is wrong because neither YAML nor JSON executes natively in browsers; JSON is parsed via JSON.parse() and YAML requires a library such as js-yaml. Option B is wrong because JSON requires double quotes on keys, while YAML permits unquoted keys, so this is a JSON trait, not a YAML-only feature. Option C is wrong because YAML uses indentation for structure but does not enforce strict block scoping the way the option implies, and JSON uses braces and brackets rather than indentation.

Answer

Native browser execution support without parsing libraries.

Answer

Strict enforcement of double quotes on all string keys.

Answer

Strict indentation-based block scoping.

Question 8

Which TWO file formats are commonly used for structuring network configuration data and automation templates in Junos DevOps pipelines? (Choose two)

Accepted Answer

JSON. JSON (A) is correct because Junos automation tooling such as PyEZ, Junos REST API, and NETCONF/RESTCONF interactions commonly serialize structured configuration and template data as JSON, which is easily parsed by Python scripts in DevOps pipelines. YAML (B) is correct because it is the native format for Ansible playbooks and Jinja2-based automation templates widely used to structure Junos configuration data declaratively in CI/CD workflows. The proprietary binary core dump format (C) is a diagnostic artifact produced on crashes, not a human-readable data-structuring format for configuration. The raw bitmap image format (D) and Windows executable format (E) are unrelated to network configuration data or automation templates and cannot represent structured configuration.

Answer

Proprietary binary core dump format

Answer

Raw bitmap image (.bmp) format

Answer

Windows executable (.exe) format

Question 9

Which TWO methods can an administrator use to verify that a Python script successfully established a NETCONF session with a Junos device? (Choose two)

Accepted Answer

Run 'show system netconf sessions' on the Junos CLI.. Option B is correct because the Junos CLI command 'show system netconf sessions' displays active NETCONF-over-SSH sessions on the device, including the session ID, client, and login time, directly confirming that the script's NETCONF session was established. Option D is correct because a PyEZ or ncclient-based script can programmatically confirm success via return objects (for example, a connected Device instance or a successful <hello> exchange) and by inspecting execution logs that record session establishment or exceptions. Option A is wrong because BGP neighbor adjacency tables reflect routing protocol state, not NETCONF session status. Option C is wrong because physical interface link LEDs only indicate Layer 1 link state and say nothing about an application-layer NETCONF session. Option E is wrong because temperature sensors report hardware environmental data unrelated to NETCONF connectivity.

Answer

Review BGP neighbor adjacency tables.

Answer

Verify physical interface link LEDs.

Answer

Check the device temperature sensors.

Question 10

Which THREE advantages are associated with using the Junos REST API over NETCONF in lightweight automation scripts? (Choose three)

Accepted Answer

Ability to traverse standard HTTP/HTTPS proxies and load balancers easily.. Option A is correct because the Junos REST API communicates over standard HTTP/HTTPS, so it traverses corporate proxies, firewalls, and load balancers using well-understood ports (80/443) without the SSH-based NETCONF transport complications. Option B is correct because REST responses can be returned in native JSON, letting lightweight scripts use built-in JSON parsers instead of requiring XML libraries such as lxml that NETCONF's XML payloads demand. Option C is correct because the REST API maps operations to familiar HTTP verbs (GET for retrieval, POST for creation/RPCs, PUT for replacement, DELETE for removal), aligning with common web development patterns and tooling. Option D is not correct because the Junos REST API still operates against the Junos configuration datastores, including the candidate configuration, so it does not eliminate them. Option E is not correct because transaction rollback is a Junos commit feature tied to Junos devices, and the REST API provides no guaranteed multi-vendor rollback across non-Juniper hardware.

Answer

Elimination of the Junos candidate configuration datastore.

Answer

Guaranteed multi-vendor transaction rollbacks across non-Juniper hardware.

Question 11

An organization is implementing a Git-based version control strategy for Junos network configurations. Which THREE practices are considered standard DevOps workflows when managing network configurations in Git? (Choose THREE)

Accepted Answer

Tagging specific repository commits to mark official production releases or maintenance versions. Option A is correct because tagging specific commits (e.g., git tag v1.0) creates immutable, human-readable references that mark official production releases or maintenance versions, enabling rollback and auditability in a Git-based DevOps workflow. Option C is correct because storing network device configuration templates as plain text files in a repository allows Git's native diff, blame, branching, and merging capabilities to track configuration changes line by line. Option D is correct because submitting configuration changes through pull requests or merge requests enforces peer review, automated CI validation, and controlled merging before changes reach production branches. Option B is incorrect because directly committing experimental changes to master bypasses review and CI gates, violating standard Git branching and change-control practices. Option E is incorrect because encrypting configuration files as binary compressed archives defeats Git's line-based diffing, merging, and review capabilities, which are core to DevOps configuration management.

Answer

Directly committing experimental production changes to the master branch without review

Answer

Encrypting all configuration text files using binary compressed archives inside Git

Question 12

Which of the following describes the fundamental structural difference between JSON and YAML regarding syntax design?

Accepted Answer

JSON relies on explicit punctuation like braces and brackets, whereas YAML relies heavily on indentation.. JSON relies explicitly on structural characters (curly braces, brackets, quotes, commas) to define hierarchies, whereas YAML primarily relies on indentation and whitespace.

Answer

YAML requires all keys to be enclosed in double quotes, whereas JSON does not.

Answer

YAML does not support lists or arrays.

Answer

JSON supports comments natively, whereas YAML does not.

Question 13

A network engineer is using Git for version control of Junos configurations. During a peer review on a pull request, a merge conflict arises because two engineers modified the same interface description line in different branches. What is the correct procedure to resolve this conflict in Git?

Accepted Answer

Manually edit the conflict markers in the affected configuration file, stage the resolved file, and complete the merge commit.. Git marks the conflicting lines in the file, requiring manual editing to choose the correct changes or combine them, followed by staging and committing the resolution.

Answer

Reboot the Junos routing engine to clear the Git repository cache and force a fast-forward merge.

Answer

Run the 'git force-merge' command to automatically discard the older branch's changes.

Answer

Use 'git reset --hard' on the remote repository to delete both conflicting branches entirely.

Question 14

Which TWO benefits are gained by using Python virtual environments when developing PyEZ and Jinja2 automation scripts? (Choose two)

Accepted Answer

They allow installing specific versions of PyEZ, lxml, and Jinja2 independently of system Python.. Option B is correct because a Python virtual environment creates an isolated site-packages directory with its own pip, so you can install pinned versions of PyEZ, lxml, and Jinja2 (e.g., pip install junos-eznc==2.6.3) without touching or conflicting with the system Python's packages. Option E is correct because that same isolation means each project's dependency set is self-contained, so upgrading a library for one automation project cannot break another project that depends on a different version. The unmarked options do not belong: virtual environments do not compile scripts into Junos binaries (A), do not replace SSH clients since PyEZ still uses NETCONF over SSH (C), and do not grant root-level CLI execution on routers (D).

Answer

They automatically compile Python scripts into binary executable files for Junos.

Answer

They remove the need to install SSH clients on the local machine.

Answer

They enable direct root-level execution of Junos CLI commands on physical routers.

Question 15

Which XML tag encapsulates the entire response returned by a Junos device in reply to a valid NETCONF RPC request?

Accepted Answer

. Every NETCONF response from a Junos device is wrapped in an tag.

Answer

<response-data>

Answer

<xml-reply>

Answer

<netconf-response>