JNCIA-DevOps Practice Test 2 — 30 Questions

Question 1

An automation engineer is writing a Python script using Juniper PyEZ to connect to a Junos device. Which context manager approach is best practice to ensure the Device session is properly closed even if an exception occurs?

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

Accepted Answer

with Device(host="192.168.1.1", user="admin", passwd="secret") as dev:. Using the 'with Device(host=...) as dev:' context manager guarantees that the open() and close() methods are handled automatically, even if runtime errors occur inside the block.

Answer

dev = Device(host="192.168.1.1"); dev.start_session()

Answer

dev = Device(host="192.168.1.1"); dev.open(autoclose=True)

Answer

dev = Device(host="192.168.1.1").connect()

Question 2

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. Software inventory and package information can be retrieved by invoking the 'get-software-information' RPC via the operational RPC URI path.

Answer

/api/configuration/system/software

Answer

/netconf/rpc/software

Answer

/api/v1/packages/status

Question 3

Which TWO configuration steps are required to enable the Junos REST API with basic security settings? (Choose two)

Accepted Answer

set system services jpagent https. To enable the REST API, you must enable the jpagent service and optionally enable HTTPS for secure transport.

Answer

set system netconf secure-mode

Answer

set protocols rest-api state active

Answer

set system services rest enable

Question 4

When managing configuration changes via PyEZ Config utility, which context manager ensures that changes are automatically rolled back if an exception occurs within the block?

Accepted Answer

with Config(dev) as cu:. The 'with Config(dev) as cu:' context manager automatically handles locking, loading, committing, and rolling back on failure.

Answer

with Config(dev, mode='private') as cu:

Answer

try: cu.lock() except: cu.rollback()

Answer

cu.commit(rollback_on_error=True)

Question 5

Which TWO error response categories or HTTP status codes are commonly returned by the Junos REST API when client requests are malformed or unauthorized? (Choose two)

Accepted Answer

401 Unauthorized. 401 Unauthorized is returned for bad or missing credentials, and 400 Bad Request is returned for malformed payload syntax.

Answer

202 Accepted

Answer

504 Gateway Timeout

Answer

100 Continue

Question 6

Which THREE architectural features distinguish the Junos REST API from traditional CLI screen-scraping (CLI automation via expect scripts)? (Choose three)

Accepted Answer

Resource-based URI routing that maps directly to configuration and operational models.. REST API provides structured data formats (JSON/XML), deterministic API contracts with HTTP status codes, and programmatic resource addressing, whereas screen-scraping relies on fragile text parsing.

Answer

Strict enforcement of synchronous modal CLI configuration blocks.

Answer

Requirement for VT100 terminal emulation buffers.

Question 7

When developing Python scripts that utilize PyEZ and Jinja2, which THREE best practices ensure robust and maintainable automation code? (Choose three)

Accepted Answer

Using the PyEZ Config context manager to ensure locks are released and rollbacks occur on error. Best practices include proper exception handling, using context managers, and separating templates from logic.

Answer

Hardcoding administrative passwords inside template files for easy rendering

Answer

Avoiding device.close() calls to keep network sessions open permanently

Question 8

An engineer is designing an automated failover script that needs to discard candidate configuration changes made via the Junos REST API. How should this discard action be performed?

Accepted Answer

Send a request to the configuration discard/rollback endpoint or invoke the discard-changes RPC via the REST API.. Discarding candidate changes in the Junos REST API is performed by invoking the discard configuration RPC or action endpoint equivalent to the NETCONF <discard-changes/> RPC.

Answer

Send an HTTP GET request with ?action=reset.

Answer

Issue an HTTP DELETE request to the root /api/configuration path.

Answer

Restart the routing engine process (RE switchover).

Question 9

When comparing the Junos REST API workflow to the NETCONF protocol workflow, which characteristic is unique to the REST API?

Accepted Answer

It requires the use of HTTP verbs such as GET, POST, PUT, and DELETE.. The Junos REST API uses standard HTTP methods (GET, POST, PUT, DELETE) and standard data formats like JSON or XML over HTTP/HTTPS, unlike NETCONF which uses XML over a dedicated TCP port (830).

Answer

It exclusively transmits data encoded in protocol buffers.

Answer

It uses connection-oriented stateful sessions over port 830.

Answer

It mandates the use of YANG schema files for every single RPC.

Question 10

An engineer is troubleshooting a script that updates Junos configuration via the REST API. The payload is sent as JSON, but the device returns a 415 Unsupported Media Type error. What is the root cause?

Accepted Answer

The Content-Type header provided in the HTTP request is missing or specifies an unsupported media type.. A 415 Unsupported Media Type error indicates that the Content-Type header sent in the HTTP request does not match what the Junos REST API daemon expects for processing configuration payloads (such as application/vnd.juniper.netconf.config+json or application/json).

Answer

The device is running out of memory buffers.

Answer

The user account does not have permission to execute PUT requests.

Answer

The target resource URI path does not exist on the device.

Question 11

When using the Junos REST API to configure static routes, how does the JSON payload structure represent list items that can have multiple instances (such as multiple next-hops or static routes)?

Accepted Answer

As JSON arrays containing objects for each list entry.. In Junos REST API JSON representations, multi-instance configuration lists are typically represented as arrays of JSON objects.

Answer

As XML CDATA blocks embedded within JSON keys.

Answer

As numerical indexed keys (e.g., 'route-0', 'route-1').

Answer

As a single concatenated string separated by semicolons.

Question 12

You are building a custom PyEZ application and need to catch exceptions specific to configuration parsing failures returned by Junos. Which exception class should your script import?

Accepted Answer

from jnpr.junos.exception import ConfigError. ConfigError is raised by PyEZ when configuration loading or committing fails.

Answer

from jnpr.junos.device import ConfigurationFailed

Answer

from jnpr.junos.utils.config import ConfigError

Answer

from jnpr.junos.exception import ParseError

Question 13

Which THREE features are provided by the Junos REST API daemon (jpagent) when running on a Junos device? (Choose three)

Accepted Answer

Translation between REST requests/JSON/XML payloads and Junos configuration/operational structures.. The jpagent daemon provides HTTP/HTTPS server capabilities, authentication handling against local/AAA databases, and translation between HTTP requests/JSON/XML and Junos internal RPC/configuration structures.

Answer

Kernel-level packet forwarding optimization for ASIC line cards.

Answer

Autonomous BGP route reflection across core routing instances.

Question 14

What is the primary benefit of using PyEZ Table and View abstractions over raw RPC XML parsing in Python scripts?

Accepted Answer

They automatically convert XML into structured Python data structures like dictionaries and lists. Tables and Views abstract complex XML trees into clean Python dictionaries and lists.

Answer

They eliminate the need to establish a Device connection object

Answer

They allow direct execution of Junos CLI operational commands without NETCONF

Answer

They automatically commit configurations to the active database

Question 15

Which statement correctly identifies the relationship between Junos REST API and NETCONF data models?

Accepted Answer

Both protocols leverage the same underlying Junos data models and management infrastructure.. Both the Junos REST API and NETCONF interface with the same underlying Junos YANG data models and management infrastructure (MGD), providing different transport and encoding wrappers for the same capabilities.

Answer

REST API bypasses all Junos data models and writes directly to kernel memory.

Answer

NETCONF uses YANG models, whereas REST API uses proprietary relational databases.

Answer

NETCONF is deprecated in favor of REST API for all Junos configuration tasks.

Question 16

When configuring advanced options for the Junos REST API jpagent, which THREE parameters or sub-statements can be configured under the 'set system services jpagent' hierarchy? (Choose three)

Accepted Answer

traceoptions. Under 'set system services jpagent', administrators can configure HTTPS, custom HTTP/HTTPS ports, and connection timeouts or limits depending on Junos software version support.

Answer

bgp-peer-group

Answer

ethernet-switching

Question 17

Which TWO statements are true regarding PyEZ Table and View definitions? (Choose two)

Accepted Answer

A View defines how individual fields within the returned XML elements are mapped to Python dictionary keys.. Tables map to RPCs and Views map to item fields using YAML.

Answer

Tables can only be used to modify device configurations, not read operational state.

Answer

Tables require Jinja2 templates to parse raw XML output.

Answer

Views replace the need to instantiate a Device object.

Question 18

An automation developer is writing a script to modify candidate configuration data on a Junos device using the REST API. Which HTTP method and request body format should be used to replace an existing configuration hierarchy?

Accepted Answer

PUT method with a JSON or XML payload representing the configuration node. To modify or replace configuration data, the PUT method is typically used in the Junos REST API configuration endpoints with JSON or XML payload.

Answer

POST method with form-urlencoded data

Answer

DELETE method with an empty body

Answer

GET method with URL parameters

Question 19

Which statement accurately describes how the Junos REST API handles configuration locking compared to NETCONF workflows?

Accepted Answer

NETCONF requires explicit lock commands, whereas the Junos REST API handles configuration locking implicitly during API-driven edit sessions.. While NETCONF explicitly supports lock and unlock protocol operations, the Junos REST API manages configuration locks implicitly or through explicit session management parameters during commit operations.

Answer

NETCONF does not support configuration locking at all.

Answer

The Junos REST API uses exclusive database locking for every GET request.

Answer

The Junos REST API requires manual SSH tunnel establishment before locks can be applied.

Question 20

Which NETCONF capability URI indicates that the server supports rolling back configuration changes to previous commit points?

Accepted Answer

Juniper specific capability strings for commit/rollback features advertised in the hello banner.. Junos supports rollback capabilities advertised via specific NETCONF capability URIs.

Answer

urn:ietf:params:netconf:capability:rollback-on-error:1.0

Answer

http://xml.juniper.net/netconf/junos/1.0

Answer

urn:ietf:params:netconf:base:1.0