JNCIA-DevOps Practice Test 12 — 15 Questions

Question 1

In a Python script utilizing PyEZ, what method must be called on the Device instance after all configuration and operational tasks are complete to properly terminate the NETCONF session?

Accepted Answer

dev.close(). In PyEZ, the Device object maintains an active NETCONF session over SSH (port 830) that must be explicitly torn down. The dev.close() method cleanly closes the NETCONF session, releases the underlying SSH transport, and frees associated resources. Without calling close(), the session may linger until timeout, consuming VTY/session slots on the Junos device.

Answer

dev.terminate()

Answer

dev.end_session()

Answer

dev.disconnect()

Question 2

What is JSNAPy primarily used for in Junos network automation?

Accepted Answer

Taking operational state snapshots and verifying device health. JSNAPy (Junos Snapshot Administrator in Python) is a Python tool that captures operational state snapshots from Junos devices and compares them against a baseline to verify health and detect drift. It is commonly used for pre/post-change validation and compliance checks. It does not compile CLI commands, perform firmware upgrades, or generate configuration templates.

Answer

Compiling Junos CLI operational commands into Python bytecode

Answer

Performing automated firmware upgrades across clusters

Answer

Generating static configuration templates

Question 3

Which TWO advantages does structured telemetry and data streaming offer over traditional SNMP polling in Junos automation? (Choose two)

Accepted Answer

High granularity and real-time visibility into operational state. Option C is correct because structured telemetry and data streaming provide high granularity and real-time visibility into operational state, delivering continuous, fine-grained metrics (e.g., via gRPC or JTI) rather than the coarse, interval-based snapshots typical of SNMP polling. Option E is correct because streaming uses a push-based model where devices proactively send data to collectors, eliminating the periodic polling overhead and associated CPU, bandwidth, and latency costs of SNMP GET/WALK cycles. The unmarked options do not belong: A is wrong because Junos devices run Junos OS, not Windows Server, and telemetry does not require it; B is wrong because analog dial-up modems are obsolete and irrelevant to modern telemetry transport; D is wrong because network interfaces are still required for connectivity and telemetry transport, so they are not eliminated.

Answer

Requiring all network devices to run Windows Server OS

Answer

Mandatory requirement for analog dial-up modems

Answer

Elimination of all network interfaces

Question 4

When interacting with Junos devices via NETCONF, which TWO RPC operations are part of standard NETCONF protocol capabilities? (Choose two)

Accepted Answer

. Option B, , is correct because it is a base NETCONF protocol operation defined in RFC 6241 that retrieves configuration data from a specified datastore (such as or ), and it is one of the mandatory capabilities every NETCONF server must support. Option E, , is also correct because it is a standard NETCONF operation from RFC 6241 used to load, merge, replace, create, or delete configuration data in a target datastore, making it a core part of NETCONF's configuration-management capabilities. The remaining options are Junos-specific or vendor-proprietary RPCs rather than standard NETCONF operations: and are Junos extension RPCs for device maintenance, and is a Junos operational RPC for troubleshooting, none of which are defined in the base NETCONF protocol specification.

Answer

<reboot-routing-engine-force>

Answer

<format-hard-drive>

Answer

<traceroute-packet>

Question 5

Which TWO HTTP response status codes indicate a successful Junos REST API request where data was successfully retrieved or modified? (Choose two)

Accepted Answer

200 OK. Option B (200 OK) is correct because the Junos REST API returns HTTP 200 when a request such as a GET successfully retrieves data or a POST/PUT successfully modifies configuration, with the response body carrying the requested representation or result. Option D (204 No Content) is correct because Junos returns HTTP 204 when an operation succeeds but there is no data to return in the body, such as a successful DELETE or a configuration change with no payload. Option A (404 Not Found) is wrong because it signals the requested resource or URI does not exist, not success. Option C (401 Unauthorized) is wrong because it indicates missing or invalid authentication credentials. Option E (500 Internal Server Error) is wrong because it indicates a server-side failure while processing the request.

Answer

404 Not Found

Answer

401 Unauthorized

Answer

500 Internal Server Error

Question 6

Which TWO methods are provided by the Python standard library 'json' module for deserializing JSON data? (Choose two)

Accepted Answer

json.loads(). Option C, json.loads(), is correct because it deserializes a JSON-formatted string (or bytes) directly into a Python object such as a dict or list. Option D, json.load(), is correct because it reads JSON data from a file-like object (for example, an open file handle) and deserializes it into a Python object. These are the two deserialization functions actually exposed by the standard library json module. Options A (json.read()), B (json.decode()), and E (json.parse()) are not functions provided by the json module, so they cannot be used for deserialization.

Answer

json.read()

Answer

json.decode()

Answer

json.parse()

Question 7

Which TWO characteristics describe declarative network automation compared to imperative scripting? (Choose two)

Accepted Answer

Defining the desired end state rather than scripting exact step-by-step CLI commands. Option B is correct because declarative network automation focuses on specifying the intended end state (for example, a desired VLAN, interface, or routing configuration) rather than writing the exact sequence of CLI commands to reach it. Option E is correct because the automation engine (such as Ansible with declarative modules, Terraform, or NSO) compares the current state to the desired state and automatically computes and applies the necessary changes, including diffs and idempotent updates. Option A is incorrect because manually logging into each router and running sequential shell commands is the opposite of declarative automation and is characteristic of manual or imperative operation. Option C is incorrect because hardcoded assembly language for packet processing is unrelated to declarative network automation and describes low-level programming, not intent-based configuration. Option D is incorrect because manually calculating diff patches for every line item is a tedious imperative task, whereas declarative systems generate the required diffs automatically.

Answer

Manually logging into each router to execute sequential shell commands

Answer

Using hardcoded assembly language for packet processing

Answer

Requiring manual calculation of diff patches for every single line item

Question 8

An automation engineer is writing a Python script using Junos PyEZ to connect to a device. Which module and class must be imported to instantiate a device object representing the Junos target?

Accepted Answer

from jnpr.junos.device import Device. Junos PyEZ provides the Device class in the jnpr.junos.device module, which is used to instantiate a device object representing a Junos target. Importing 'from jnpr.junos.device import Device' is the correct way to create a Device instance and connect to a Junos device. This is the foundational import for any PyEZ automation script.

Answer

from jnpr.junos.rpcs import RPC

Answer

from jnpr.junos.facts import Facts

Answer

from jnpr.junos.utils.sw import SW

Question 9

You need to execute a custom remote procedure call (RPC) in PyEZ to retrieve the Ethernet switching table. The tag in Junos XML API is get-ethernet-switching-table-information. How should you write this method call in Python?

Accepted Answer

dev.rpc.get_ethernet_switching_table_information(). PyEZ maps XML RPC hyphens to Python underscores, allowing you to call rpc methods directly as attributes on dev.rpc.

Answer

dev.rpc.get-ethernet-switching-table-information()

Answer

dev.get_ethernet_switching_table_information()

Answer

dev.execute_rpc('get-ethernet-switching-table-information')

Question 10

An automation developer is designing a tool that interacts with multiple network vendors, including Juniper Junos. They evaluate using Junos REST API versus NETCONF. Which workflow advantage does the REST API offer over NETCONF in web-centric application environments?

Accepted Answer

REST API leverages standard HTTP/HTTPS transport infrastructure, making it easily traversable through web proxies and adaptable to modern web frameworks using native JSON.. REST APIs natively integrate with standard HTTP load balancers, web proxies, firewalls inspectable by HTTP/HTTPS, and standard web application frameworks without needing specialized SSH tunnel management or XML parser libraries.

Answer

REST API completely replaces the Junos candidate configuration datastore with a real-time database.

Answer

REST API natively supports XML parsing, whereas NETCONF only supports binary protocols.

Answer

REST API guarantees atomic multi-device commits across different vendors without controllers.

Question 11

Which THREE advanced features or methods are available on a PyEZ Device instance for session management and inspection? (Choose three)

Accepted Answer

dev.timeout property to get or set NETCONF RPC timeout values. Option A is correct because a PyEZ Device object exposes a timeout property that lets you get or set the NETCONF RPC timeout value used for requests. Option B is correct because the connected property returns a boolean indicating whether the NETCONF session to the device is currently active. Option C is correct because the capabilities attribute returns the list of NETCONF server capability URIs advertised by the device, useful for feature inspection. Option D is not a real PyEZ Device method; refreshing facts is done via facts_refresh(), not reload_session(). Option E is not a valid PyEZ Device attribute; commit timeouts are handled through configuration/commit options rather than a commit_timeout property.

Answer

dev.reload_session() for refreshing device facts

Answer

dev.commit_timeout for software installation timing

Question 12

When an automation script issues a POST request to create a new static route via the Junos REST API, what HTTP status code indicates that the resource was successfully created?

Accepted Answer

201 Created. In standard HTTP REST semantics, a successful creation request resulting in a new resource returns HTTP status code 201 Created.

Answer

200 OK

Answer

302 Found

Answer

204 No Content

Question 13

In the context of network DevOps, what is the purpose of implementing idempotency in automation scripts or playbooks targeting Junos devices?

Accepted Answer

To ensure that running the same configuration task multiple times produces the exact same desired state without making redundant changes if already applied.. Idempotency ensures that running the same automation task multiple times yields the same result without making unintended changes if the state is already correct.

Answer

To encrypt all configuration payloads using AES-256 before transport.

Answer

To ensure that every script execution generates a completely random new configuration to test device resilience.

Answer

To force the Junos Routing Engine to reboot every time a script is executed.

Question 14

Which THREE statements correctly contrast the session handling of NETCONF versus the Junos REST API? (Choose three)

Accepted Answer

NETCONF maintains a persistent, stateful connection over an SSH session with capability exchanges.. Option A is correct because NETCONF operates over a persistent SSH transport (typically TCP port 830) and establishes a stateful session that begins with a hello message exchanging capabilities between client and server. Option D is correct because the Junos REST API authenticates each request individually using standard HTTP headers (such as Authorization with Basic credentials or an X-Auth-Token) rather than relying on an interactive shell session. Option E is correct because the Junos REST API follows the stateless HTTP request/response model, where each transaction is independent and no session context is retained between calls. Option B is incorrect because NETCONF does not use HTTP or port 80; it runs over SSH, and HTTP is the transport for REST, not NETCONF. Option C is incorrect because NETCONF sessions do not expire every 30 seconds based on keystrokes; they persist until explicitly closed or timed out by configured idle limits.

Answer

NETCONF requires an HTTP web server running on port 80 to maintain session state.

Answer

NETCONF sessions automatically expire every 30 seconds if an interactive keystroke is not received.

Question 15

You are writing a Python script to retrieve interface statistics from a Junos device using the REST API. You use HTTP Basic Authentication. Which HTTP header must be included to pass the encoded credentials correctly?

Accepted Answer

Authorization. HTTP Basic Authentication requires the 'Authorization' header containing the keyword 'Basic' followed by the Base64-encoded username:password string.

Answer

Proxy-Authenticate

Answer

Junos-Auth-Token

Answer

X-API-Key