JNCIA-DevOps Practice Test 16 — 15 Questions

Question 1

An engineer executes an HTTP GET request to retrieve interface operational details using the Junos REST API, but receives a 403 Forbidden status code. What is the most likely reason?

Accepted Answer

The authenticated user account lacks sufficient RBAC permissions to access the requested resource.. A 403 Forbidden status code indicates that the authentication credentials provided were valid (otherwise it would be 401), but the user account lacks the necessary RBAC permissions or class privileges to access the requested resource.

Answer

The HTTP request method should have been POST.

Answer

The Accept header was missing from the GET request.

Answer

The jpagent service is disabled on the device.

Question 2

You are configuring a CI/CD pipeline for Junos network deployments. The pipeline must validate the syntax of generated candidate configurations against a physical or virtual Junos device before committing them to production. Which stage of the CI/CD pipeline does this validation step represent?

Accepted Answer

Continuous Integration validation stage. The validation of candidate configuration syntax against a Junos device before committing to production is a pre-merge quality gate, which is the essence of the Continuous Integration (CI) validation stage. In CI, every code change triggers automated builds and tests to catch errors early. Here, the 'code' is the generated Junos configuration, and the test is a syntax check using the device's configuration parser (e.g., via `commit check` or loading the config with `load merge` and `commit check`). This ensures that only syntactically valid configurations proceed to deployment, preventing broken commits from reaching production.

Answer

Continuous Deployment stage

Answer

Continuous Monitoring stage

Answer

Infrastructure Provisioning stage

Question 3

Which command is used in Git to save staged changes to the local repository with a descriptive commit message?

Accepted Answer

git commit -m "message". The `git commit -m "message"` command records the staged changes to the local repository with the provided commit message. It is the standard Git command for creating a commit from the staging area. The `-m` flag allows the message to be specified inline.

Answer

git add

Answer

git push

Answer

git save

Question 4

A network architect is designing a version control strategy for multi-vendor network operations. They need a system that tracks changes to text-based configuration files, allows multiple engineers to work on separate feature branches concurrently, and merges changes systematically. Which category of tool is being utilized?

Accepted Answer

Distributed Version Control System (DVCS). Git and similar tools are Distributed Version Control Systems (DVCS) designed to track file revisions and manage collaborative workflows through branching and merging.

Answer

Network Management System (NMS) poller

Answer

Network Configuration Protocol (NETCONF) manager

Answer

Dynamic Host Configuration Protocol (DHCP) server

Question 5

Which user credential validation mechanism does the Junos REST API use by default when authenticating incoming API calls?

Accepted Answer

Junos local user database or AAA via HTTP Basic Authentication. The Junos REST API authenticates incoming requests against the Junos local user database or configured AAA servers (RADIUS/TACACS+) using standard HTTP Basic Authentication.

Answer

OAuth 2.0 bearer tokens generated by an external IdP

Answer

Pre-shared API secret keys stored in environment variables

Answer

SSH public key authentication exclusively

Question 6

Which TWO actions can be performed using the JSNAPy command-line interface (CLI) tool during network verification workflows?

Accepted Answer

Capturing operational state snapshots of devices defined in configuration files. JSNAPy (Junos Snapshot Administrator in Python) is a CLI tool designed for network verification workflows, and option A is correct because its core function is to capture operational state snapshots from devices listed in the jsnapy.cfg configuration file using commands like 'jsnapy --snapcheck' or 'jsnapy --snap'. Option C is also correct because JSNAPy's primary purpose is to compare pre-change and post-change snapshots against test assertions defined in YAML test files, executed via 'jsnapy --check' or 'jsnapy --diff', to validate that network state matches expected values. The unmarked options do not belong: ZTP DHCP server scope provisioning (B) is a configuration task unrelated to JSNAPy's snapshot/verification role, compiling Junos routing daemon binaries (D) is an internal Juniper build process not exposed through JSNAPy, and translating PyEZ scripts into SLAX op scripts (E) is not a JSNAPy capability since JSNAPy consumes PyEZ but does not perform such translation.

Answer

Provisioning zero-touch deployment (ZTP) DHCP server scopes on core switches

Answer

Directly compiling Junos Source routing daemon binaries

Answer

Translating PyEZ Python scripts into native Junos SLAX op scripts

Question 7

A network automation team is using the Junos REST API to manage configurations on a Junos device. They need to perform a commit operation that includes a commit comment and also synchronizes the commit across all Routing Engines in a dual-RE system. Which HTTP method and URI combination should they use to achieve this with a single request?

Accepted Answer

POST to /rpc/commit with an XML body including and . To execute a commit with a comment and synchronization, the Junos REST API requires a POST request to /rpc/commit with an XML body containing the and elements. This leverages the RPC mechanism, allowing multiple commit options in one request. Other methods and endpoints do not support this functionality.

Answer

POST to /rpc/commit with a JSON body containing and

Answer

PUT to /config/commit with a JSON body specifying comment and synchronize

Answer

PATCH to /rpc/commit with a JSON body containing comment and synchronize attributes

Question 8

An automation engineer uses a Python script to pull interface statistics from a Junos device through the Junos PyEZ Table and View framework. The View definition must map the XML element <name> to the Python attribute interface_name. Which PyEZ View syntax correctly performs this mapping?

Accepted Answer

interface_name: name. A PyEZ View is a YAML mapping where each key is the Python attribute to expose and each value is the corresponding XML element or path. Writing the attribute first and the XML element second correctly maps <name> to interface_name, allowing the Table to populate rows with the expected attribute.

Answer

interface_name: { name: name }

Answer

interface_name = name

Answer

name: interface_name

Question 9

An automation engineer uses a Python script with the PyEZ library to retrieve interface statistics from a Junos device and wants to store the results in a file that preserves data types such as integers, booleans, and null values for later processing by another tool. The engineer needs a serialization format that is compact, widely supported by APIs, and preserves these primitive types. Which format should the engineer choose?

Accepted Answer

JSON. JSON is designed around a small set of primitive types and is the standard payload format for REST APIs and streaming telemetry, so it preserves integers, booleans, and null exactly as Python represents them. Its compact syntax and universal parser support make it the best choice for handing structured data to another tool. YAML is readable but less strict, XML loses native types, and CSV is flat and text-only.

Answer

XML

Answer

CSV

Answer

YAML

Question 10

A network automation engineer is establishing a NETCONF session with a Junos device. After the SSH connection is established, the device and the client exchange <hello> messages. What is the primary purpose of this exchange?

Accepted Answer

To negotiate NETCONF capabilities and session parameters.. The <hello> messages are exchanged immediately after the SSH connection to advertise and negotiate NETCONF capabilities. This includes the base protocol version, supported datastores, and other features. It ensures that both the client and server understand what operations are available before any RPCs are sent. It does not authenticate, synchronize clocks, or transfer configuration.

Answer

To synchronize the device's clock with the client's clock.

Answer

To authenticate the client and establish a secure channel.

Answer

To transfer the initial configuration from the device to the client.

Question 11

A developer is writing a script that uses the Junos REST API to make configuration changes. The script needs to handle errors gracefully. After sending a load-configuration RPC, the developer receives an HTTP 400 Bad Request response with a JSON body containing an error message. What is the most likely cause of this error?

Accepted Answer

The configuration payload contains a syntax error or invalid statement.. An HTTP 400 Bad Request in response to a load-configuration RPC indicates that the request was syntactically incorrect or contained invalid configuration data. Common causes include malformed JSON, invalid Junos configuration statements, or incorrect parameter values. The error response body usually contains a detailed message pointing to the specific issue. Authentication failures yield 401, permission issues yield 403, and a missing commit would not cause an immediate error. Therefore, the most likely cause is a syntax error in the configuration payload.

Answer

The user account used for authentication lacks the necessary permissions.

Answer

The REST API service is not enabled on the Junos device.

Answer

The commit RPC was not called after the load-configuration RPC.

Question 12

An engineer is using Junos PyEZ to load a configuration change onto a device. The script uses the Config class to lock the candidate configuration, load a set of changes, and then commit. During testing, the commit fails because another user has an exclusive lock on the configuration. What is the correct behavior of the engineer's script when it attempts to lock the configuration in this situation?

Accepted Answer

The lock operation will fail immediately with an error indicating that the configuration is already locked by another user.. When a Junos device configuration is already locked by another session, an attempt to acquire a lock fails immediately with an error. In this scenario, the PyEZ script would receive an exception at the lock step, preventing it from loading changes. The engineer must handle this error, perhaps by retrying later or by using a different coordination mechanism. This immediate failure is a safety feature that prevents conflicting configuration modifications and preserves configuration integrity across concurrent management sessions.

Answer

The lock operation will automatically override the existing lock and proceed with the configuration load.

Answer

The lock operation will block indefinitely until the other user releases the lock, then proceed automatically.

Answer

The lock operation will succeed but the commit will fail later because of the conflicting lock.

Question 13

An automation engineer is comparing YAML and JSON for storing Junos device configuration data. Which TWO statements accurately describe differences between the two formats? (Choose two.)

Accepted Answer

YAML uses indentation to represent structure, while JSON uses braces and brackets.. YAML and JSON differ in syntax and features. YAML uses indentation for structure and supports comments, while JSON uses braces and brackets and does not allow comments. These differences make YAML more human-friendly for configuration files, whereas JSON is more compact and widely supported by APIs. The other statements misstate the capabilities or the superset relationship between the formats.

Answer

JSON is a superset of YAML, meaning all YAML documents are valid JSON.

Answer

JSON supports anchors and aliases for reusing content, while YAML does not.

Answer

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

Question 14

You are writing a Python script that uses PyEZ to connect to a Junos device. After calling `dev.open()`, you need to verify that the NETCONF session is active before performing operational commands. Which statement correctly checks the connection status and returns a Boolean value?

Accepted Answer

`dev.connected`. The `connected` property is a read-only Boolean that reflects whether the NETCONF session is currently open. After calling `open()`, checking `dev.connected` confirms the session is active before sending operational commands. Other options are not valid PyEZ attributes or methods for this check.

Answer

`dev.is_open()`

Answer

`dev.status()`

Answer

`dev.session`

Question 15

Which protocol is natively used by Junos XML management APIs to provide structured, session-oriented configuration and operational data exchange?

Accepted Answer

NETCONF. NETCONF is the session-oriented protocol used for Junos XML management.

Answer

FTP

Answer

Syslog

Answer

Telnet