JNCIA-DevOps Junos Automation Stack And DevOps Concepts Practice Test 2 — 15 Questions

Question 1

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.

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

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

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.

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Continuous Deployment stage

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Continuous Monitoring stage

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Infrastructure Provisioning stage

Question 3

Your CI/CD pipeline includes a linters step before deployment. Why is running a linter against YAML or Jinja2 template files critical in a Junos automation workflow?

Accepted Answer

To detect syntax errors, indentation issues, and style violations in template and data files before deployment.. Linters analyze source code or configuration files for syntax errors, indentation issues, and style violations without executing them. In a Junos automation workflow, running a linter against YAML or Jinja2 templates before deployment catches errors early, preventing failed deployments and reducing troubleshooting time. This is critical because YAML is indentation-sensitive and Jinja2 templates can have syntax errors that only surface at render time.

Answer

To compile YAML files into Junos microcode for the Packet Forwarding Engine.

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To automatically execute unit tests against live BGP peering sessions.

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To encrypt sensitive passwords stored within plaintext configuration files.

Question 4

A network engineer is using Git for version control of Junos configurations. During a peer review on a pull request, a merge conflict arises because two engineers modified the same interface description line in different branches. What is the correct procedure to resolve this conflict in Git?

Accepted Answer

Manually edit the conflict markers in the affected configuration file, stage the resolved file, and complete the merge commit.. Git marks the conflicting lines in the file, requiring manual editing to choose the correct changes or combine them, followed by staging and committing the resolution.

Answer

Reboot the Junos routing engine to clear the Git repository cache and force a fast-forward merge.

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Run the 'git force-merge' command to automatically discard the older branch's changes.

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Use 'git reset --hard' on the remote repository to delete both conflicting branches entirely.

Question 5

An automation engineer is designing a deployment strategy for Junos devices using Git branches. Which branching strategy model aligns best with continuous delivery where feature branches are merged frequently into a shared integration branch that automatically triggers staging tests?

Accepted Answer

Trunk-based development where developers merge small, frequent changes into a central main branch that drives automated pipelines.. Trunk-based development aligns best with continuous delivery because developers merge small, frequent changes into a central main branch, which automatically triggers staging tests via CI/CD pipelines. This reduces merge conflicts, shortens feedback loops, and keeps the main branch always deployable.

Answer

Creating a separate permanent branch for every physical router in the network and never merging them.

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Locking the master branch for 12 months while developing a single monolithic configuration update offline.

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Using tag-based releases exclusively without utilizing any version control branches.

Question 6

You are reviewing a pull request that updates Junos interface configurations using Jinja2 templates. The template contains a conditional statement checking an interface speed variable. What happens if the variable is undefined during template rendering?

Accepted Answer

Jinja2 raises an undefined error and halts template rendering unless default filters or conditional checks are used.. Jinja2 raises an UndefinedError by default when an undefined variable is evaluated in a template, unless configured otherwise or handled with defined tests.

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The Git repository automatically rejects the push citing syntax errors.

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Junos automatically ignores the missing variable and applies default factory settings.

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The target Junos router enters rescue mode due to corrupted NETCONF RPC messages.

Question 7

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.

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It compresses the configuration database to save NVRAM storage space.

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

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

Question 8

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.

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

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

Question 9

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

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Syslog

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Telnet

Question 10

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.

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Siloing network operations strictly away from software development teams.

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Eliminating all documentation in favor of verbal communication.

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

Question 11

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.

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git add

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git push

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git save

Question 12

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.

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

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

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

Question 13

Why is it considered a best practice to store sensitive secrets (such as SNMP community strings or API tokens) outside of plaintext Jinja2 templates in a Git repository?

Accepted Answer

To prevent unauthorized exposure of credentials in shared version control systems, utilizing secure secret management tools instead.. Storing secrets in plaintext in version control risks exposure of sensitive credentials to anyone with repository access.

Answer

Because Junos devices do not accept authentication strings longer than 8 characters.

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To prevent Jinja2 rendering engines from running out of memory.

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To ensure that NETCONF sessions always default to unencrypted plain text.

Question 14

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.

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

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To compile Python automation scripts into binary executables.

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

Question 15

A network engineer writes a Python script using Junos PyEZ to push a configuration change. The script uses the ConfigTable or Config class. What mechanism does PyEZ use under the hood to ensure the configuration lock is released even if the script encounters an unhandled exception?

Accepted Answer

Python context managers ('with' statements) that automatically release locks and clean up session state upon exit.. Python context managers (using the 'with' statement) automatically handle acquiring and releasing locks and rolling back candidate changes on exception in PyEZ.

Answer

NETCONF keepalive timers that drop the SSH session after 1 second.

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A UNIX cron job that reboots the router every 5 minutes.

Answer

Hardware watchdog timers built into the Routing Engine ASIC.