JNCIA-DevOps Practice Test 7 — 10 Questions

Question 1

When writing a Python script that connects to multiple Junos devices concurrently using PyEZ, which Python module is commonly used to manage thread pooling and parallel execution?

Accepted Answer

concurrent.futures. The concurrent.futures module is the standard Python library for managing thread pools and parallel execution. It provides ThreadPoolExecutor and ProcessPoolExecutor, which are commonly used with PyEZ to connect to multiple Junos devices concurrently. This is the recommended approach for parallel device operations in Python scripts.

Answer

jnpr.junos.parallel

Answer

multiprocessing.device

Answer

asyncio.netconf

Question 2

In a DevOps pipeline managing Junos devices, an engineer implements 'Infrastructure as Code' (IaC). Which practice best exemplifies this methodology when applied to Junos routing policies?

Accepted Answer

Defining routing policies in Jinja2 templates and YAML data files, committing them to Git, and automatically pushing them via Ansible playbooks.. IaC defines infrastructure in declarative configuration files stored in version control, allowing automated testing and deployment.

Answer

Writing custom Python scripts that use regex to parse 'show route' outputs on the fly.

Answer

Manually logging into each router via SSH during a maintenance window to type out policy-options statements.

Answer

Using dynamic routing protocols like BGP to automatically advertise prefixes without human intervention.

Question 3

An engineer needs to explain the primary advantage of treating network configurations as code in a modern DevOps workflow. Which principle best describes this approach?

Accepted Answer

Storing configurations in a version control system to track history, enable rollbacks, and facilitate collaboration.. Treating network configurations as code allows infrastructure to be version-controlled, repeatedly deployed, and tested just like software code.

Answer

Immutable infrastructure deployment where devices are replaced rather than updated manually.

Answer

Compiling the network CLI commands into binary machine code before executing them on Junos devices.

Answer

Automating the complete removal of the command-line interface in favor of graphical topology builders.

Question 4

When writing a Python script to interact with Junos devices, you want to ensure that password credentials are not hardcoded in the source code. What is a recommended best practice supported by PyEZ?

Accepted Answer

Using SSH key-based authentication or environment variables/config files (.junodes). PyEZ natively supports configuration files like ~/.junodes or passing parameters dynamically, but also respects environment variables or SSH keys.

Answer

Disabling authentication in the script

Answer

Storing credentials in plaintext in a public GitHub repository

Answer

Hardcoding credentials in base64 encoding

Question 5

You send an edit-config RPC with an invalid XML tag name. What is the standard structure of the error returned in the <rpc-reply>?

Accepted Answer

An element containing diagnostic sub-elements like and .. NETCONF errors are returned inside an element containing details such as error-type, error-tag, and error-message.

Answer

A standard Linux kernel panic log string.

Answer

An HTTP 400 Bad Request status code.

Answer

A syslog message printed directly to the terminal emulator.

Question 6

Which TWO statements are true regarding the NETCONF protocol hello message exchange? (Choose two.)

Accepted Answer

Both client and server exchange capabilities using XML elements containing URI strings.. Option C is correct because in the NETCONF hello exchange both peers send a element containing a list, where each capability is expressed as a URI string (for example urn:ietf:params:netconf:base:1.0 or urn:ietf:params:netconf:capability:candidate:1.0), allowing each side to learn the other's supported features. Option D is correct because the server's hello includes a element, a positive integer attribute that uniquely identifies the NETCONF session for the duration of that connection. Option A is wrong because database locking is performed later with operations, not during the hello exchange, and the hello occurs before any configuration operations. Option B is wrong because the client hello advertises supported capabilities, not a list of YANG modules it intends to modify. Option E is wrong because the hello exchange is mandatory in NETCONF regardless of the SSH authentication method used.

Answer

The client uses the hello message to lock the configuration database before session initialization.

Answer

The client hello message must include the list of YANG modules it intends to modify during the session.

Answer

The hello message exchange is optional if a pre-shared SSH key is used for authentication.

Question 7

An automation engineer is writing a Python script that uses the ncclient library to connect to a Junos device via NETCONF. The engineer wants to retrieve the entire candidate configuration from the device. Which NETCONF operation should be used?

Accepted Answer

with source set to . To retrieve the candidate configuration via NETCONF, the correct operation is with the source datastore specified as . This operation reads configuration data from the chosen datastore. Other operations like target running state and configuration, modifies datastores, and changes configuration. Therefore, is the proper choice.

Answer

<get> with a subtree filter for configuration

Answer

<copy-config> from running to candidate

Answer

<edit-config> with operation 'get'

Question 8

In a Junos automation environment, what role does a schema (such as YANG or Junos XSD) play when interacting with NETCONF?

Accepted Answer

It defines the structural rules, data types, and valid hierarchy for configuration and operational data models.. YANG or XSD schemas define the data model structure, types, and constraints for configuration and operational data.

Answer

It encrypts the communication channel between the client and the Junos device.

Answer

It acts as a firewall filter blocking unauthorized IP addresses on the management interface.

Answer

It compiles Python scripts into executable machine code for the Routing Engine CPU.

Question 9

An automation engineer stores Junos interface descriptions in a YAML file. One description includes the text 'Link: 10G uplink to core-sw-01'. After loading the file with a standard YAML parser, the engineer finds the value is not parsed as expected. Which YAML syntax should the engineer use to store this value correctly?

Accepted Answer

Wrap the value in double quotes: "Link: 10G uplink to core-sw-01". YAML plain scalars cannot contain a colon followed by a space because that sequence signals a mapping key-value separator. Quoting the scalar with double quotes (or single quotes) tells the parser to treat the entire content as a literal string. This preserves the description exactly as intended so Junos configuration templates receive the correct value.

Answer

Prefix the value with an ampersand: &Link: 10G uplink to core-sw-01

Answer

Enclose the value in square brackets: [Link: 10G uplink to core-sw-01]

Answer

Escape the colon with a backslash: Link\: 10G uplink to core-sw-01

Question 10

You are writing a script that uses Jinja2 to dynamically render a Junos interface configuration. Which Python module and function are required to load a template from the local filesystem and render it with a dictionary of variables?

Accepted Answer

from jinja2 import Environment, FileSystemLoader. The standard Jinja2 API for loading templates from disk is to create an Environment with a FileSystemLoader pointed at the template directory, then call get_template() and render() with a variable dictionary. This is the canonical Python Jinja2 pattern and works directly with Junos config templates. PyEZ does not provide its own Jinja2 wrapper module for this purpose.

Answer

from jnpr.junos.cfg import ConfigTemplate

Answer

from jnpr.junos.template import TemplateRenderer

Answer

import jnpr.junos.utils.jinja as jinja