JNCIA-DevOps Practice Test 14 — 15 Questions

Question 1

What is a primary characteristic of a DevOps culture when applied to network operations (NetOps)?

Accepted Answer

Emphasizing collaboration, automation, continuous testing, and shared responsibility between network and development teams.. NetOps applies DevOps principles like collaboration, automation, and CI/CD to network engineering.

Answer

Siloing network operations strictly away from software development teams.

Answer

Eliminating all documentation in favor of verbal communication.

Answer

Relying entirely on manual change approval boards for every minor configuration change.

Question 2

Which THREE principles are foundational to the DevOps movement when applied to network engineering? (Choose three)

Accepted Answer

Continuous monitoring and feedback loops for network telemetry. Foundational DevOps principles include automation, continuous feedback, culture/collaboration, and transparency.

Answer

Strict siloing of operational teams from software developers

Answer

Relying solely on annual manual network audits

Question 3

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 4

What is the primary function of a version control system (VCS) like Git in a Junos automation workflow?

Accepted Answer

To track configuration history, enable collaboration, and provide a single source of truth for network designs.. A VCS tracks changes over time, enabling collaboration, rollback, and audit trails.

Answer

To act as a high-speed packet forwarding engine for BGP routes.

Answer

To compile Python automation scripts into binary executables.

Answer

To monitor real-time CPU utilization on Junos routing engines.

Question 5

An automation engineer is writing a Python script to push configurations to a Junos device. The script loads a YAML data file containing interface descriptions. One description contains a colon without a following space (e.g., 'Interface:Primary'). What error will PyYAML raise when attempting to parse this file?

Accepted Answer

ScannerError. In YAML, a colon must be followed by a whitespace character to be recognized as a mapping key-value separator. If no space follows, PyYAML raises a ScannerError or MappingValuesError.

Answer

TypeError

Answer

YAMLSemanticError

Answer

JSONDecodeError

Question 6

You are writing a Python automation script that processes configuration data. The script reads a YAML file containing Junos firewall filters, modifies them, and writes them back out. However, you notice that all the original comments in the file are stripped out in the output. What is the fundamental reason for this behavior in standard PyYAML dump operations?

Accepted Answer

Comments are stripped during parsing because they are not part of the YAML data model.. PyYAML parses YAML files into abstract syntax trees (AST) or Python native data structures, discarding comments during the parsing phase because comments are not part of the data model.

Answer

The yaml.safe_dump() function explicitly deletes comments for security reasons.

Answer

YAML specification mandates that all comments are ephemeral and cannot be serialized.

Answer

Comments must be re-injected using the 'preserve_comments=True' parameter.

Question 7

When designing a version control workflow for Junos configurations using Git, which THREE practices are considered industry best standards? (Choose three)

Accepted Answer

Using feature branches for developing new configuration changes before merging into main. Best practices include code reviews via pull requests, using feature branches, and keeping secrets out of code.

Answer

Completely bypassing automated testing to speed up deployments

Answer

Storing plaintext administrative passwords directly in public Git repositories

Question 8

An automation engineer wants to verify the syntax of a large YAML playbook before executing it against a production Junos device. Which python one-liner command can be run in the terminal to quickly check if the file is syntactically valid YAML?

Accepted Answer

python3 -c 'import yaml, sys; yaml.safe_load(open(sys.argv[1]))' config.yaml. Running python3 -c 'import yaml, sys; yaml.safe_load(open(sys.argv[1]))' filename.yaml attempts to parse the file and will report any syntax errors.

Answer

yaml --validate config.yaml

Answer

netconf-console --check config.yaml

Answer

python3 -m json.tool config.yaml

Question 9

When serializing Python data structures to JSON for Junos automation payloads, which THREE parameters can be passed to json.dumps() to control formatting and readability? (Choose three)

Accepted Answer

separators. Parameters like indent, sort_keys, and separators are standard formatting arguments for json.dumps().

Answer

max_depth

Answer

strict_mode

Question 10

An operations team is applying DevOps principles to network automation on Junos devices. They want to ensure that all changes to device operational states and configurations are treated as disposable and repeatable. Which DevOps practice best describes rebuilding device configurations completely from centralized version-controlled templates rather than performing manual incremental hot-patches?

Accepted Answer

Immutable infrastructure and declarative provisioning. Infrastructure as Code (IaC) and immutable infrastructure treat configurations as reproducible artifacts generated from source control rather than mutable, long-lived states modified ad-hoc.

Answer

Stateful configuration drift management

Answer

Blue-green circuit provisioning

Answer

Event-driven telemetry ingestion

Question 11

When managing Junos configuration changes in a team environment, why is atomic configuration rollback capability crucial during automated deployments?

Accepted Answer

It ensures that either all configuration statements in a transaction are applied successfully or none are, preventing partial/corrupt states.. Atomic rollbacks ensure that if a change set fails validation or causes a network fault, the system can revert cleanly to the previous working state without partial application.

Answer

It compresses the configuration database to save NVRAM storage space.

Answer

It allows the router to dynamically rewrite Python scripts into C++ for faster execution.

Answer

It automatically backs up the entire Junos OS image to an external TFTP server.

Question 12

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 13

Which NETCONF RPC tag is used to gracefully terminate an active NETCONF session with a Junos device?

Accepted Answer

. The RPC requests graceful termination of the NETCONF session.

Answer

<terminate-session>

Answer

Answer

<kill-session>

Question 14

Which Junos configuration statement enables the NETCONF service over SSH for remote automation clients?

Accepted Answer

set system services netconf ssh. Enabling NETCONF on Junos requires configuring the system services netconf ssh hierarchy.

Answer

set protocols netconf enable

Answer

set netconf ssh-server enable

Answer

set system xml-api netconf enable

Question 15

When designing an automation workflow that uses the Junos REST API for configuration management, which THREE practices ensure robust execution? (Choose three)

Accepted Answer

Configure HTTPS (jpagent https) to encrypt credentials and configuration payloads in transit.. Robust REST workflows should handle HTTP status codes, use HTTPS for secure transport, and properly structure payloads with appropriate Content-Type headers.

Answer

Always reboot the Routing Engine after every GET request.

Answer

Send raw VT100 terminal escape sequences inside the HTTP body.