JNCIA-DevOps Multiple Select — 30 Questions

Question 1

An automation engineer is reviewing data serialization formats used within Junos automation workflows. Which TWO statements are correct regarding JSON syntax and data types? (Choose two)

Accepted Answer

JSON object keys must be enclosed in double quotes.. Option C is correct because JSON (RFC 8259) requires that every object member name, i.e., every key, be a string enclosed in double quotes, so keys like {"host": "router1"} are valid while {host: "router1"} is not. Option D is correct because JSON defines exactly six value types — string, number, object, array, boolean (true/false), and null — and the literal keyword null is the valid representation of the null data type, commonly used in Junos automation payloads to indicate an absent or empty value. Option A is incorrect because JSON strings must use double quotes; single quotes are not valid JSON (they are only tolerated by some lenient parsers such as Python's ast.literal_eval or YAML). Option B is incorrect because standard JSON has no comment syntax at all, so a '#' character would be invalid — comments are only available in JSON5, JSONC, or YAML. Option E is incorrect because JSON forbids trailing commas after the last element of an array or the last member of an object, and such input will fail strict parsing.

Answer

Single quotes can be used interchangeably with double quotes for strings.

Answer

JSON supports inline comments starting with the '#' symbol.

Answer

Trailing commas are permitted in both arrays and objects.

Question 2

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.. Option A is correct because the Junos REST API is exposed over HTTPS via the jpagent (Juniper Web Agent) service, so enabling HTTPS (jpagent https) ensures that credentials and configuration payloads are encrypted in transit rather than sent in cleartext. Option B is correct because the REST API requires the client to declare the payload format with the proper Content-Type header (for example, application/json for JSON or application/xml for XML); an incorrect or missing header causes the request to be rejected or misparsed. Option D is correct because robust automation must inspect HTTP response status codes — 200 for successful GETs, 201 for created resources, and 204 for successful operations with no content — to confirm the request succeeded before proceeding. Option C is not appropriate because GET requests are read-only and rebooting the Routing Engine after each one would be disruptive and unnecessary. Option E is not appropriate because the REST API exchanges structured JSON or XML over HTTP, not raw VT100 terminal escape sequences, which belong to interactive CLI sessions.

Answer

Always reboot the Routing Engine after every GET request.

Answer

Send raw VT100 terminal escape sequences inside the HTTP body.

Question 3

When writing an automation script that converts data formats between YAML and JSON for Junos configuration pipelines, which THREE potential pitfalls should an engineer account for? (Choose three)

Accepted Answer

JSON integer keys are automatically converted to strings in Python dictionaries.. Option C is correct because JSON object keys are always strings, so when Python's json module loads a JSON document, any key that appears numeric (e.g., 1) becomes the string '1', which can break lookups or round-trips if the script expects an integer key. Option D is correct because JSON has no comment syntax, so any YAML comments (# ...) are discarded by the YAML parser and cannot be represented in the resulting JSON output. Option E is correct because YAML 1.1 parsers interpret unquoted scalars such as 'yes'/'no' as booleans and leading-zero values like 012 as octal integers, silently changing the data type unless the scalars are explicitly quoted. Option A is wrong because YAML does not guarantee lossless round-trip conversion for arbitrary Python objects (custom types, tuples, sets, etc. require tags or custom representers). Option B is wrong because JSON has no native support for YAML anchors and aliases; those are YAML-specific features that must be resolved before JSON serialization.

Answer

YAML automatically guarantees lossless round-trip conversion for all Python objects.

Answer

JSON files natively support YAML anchors and aliases.

Question 4

Which TWO data serialization formats can an automation engineer request using the 'Accept' header in a Junos REST API GET request? (Choose two)

Accepted Answer

application/json. The Junos REST API supports content negotiation through the HTTP Accept header, and the two media types it recognizes for structured data responses are application/json (option C) and application/xml (option D); requesting either of these causes the device to return the RPC reply serialized in JSON or XML respectively. JSON is the default and most commonly used format for automation tooling, while XML mirrors the native Junos XML API output, so both are valid and correct. The remaining options are not supported by the Junos REST API: application/yaml (A) is not a media type Junos negotiates, text/csv (B) is not a serialization format the API emits, and application/octet-stream (E) denotes an opaque binary stream rather than a structured serialization format.

Answer

application/yaml

Answer

text/csv

Answer

application/octet-stream

Question 5

Which TWO characteristics distinguish the Junos REST API from NETCONF when interacting with Junos devices? (Choose two)

Accepted Answer

The REST API uses standard HTTP methods (GET, POST, PUT, DELETE) over HTTP/HTTPS ports.. Option C is correct because the Junos REST API is an HTTP-based interface that uses standard HTTP verbs (GET to retrieve, POST to create/execute RPCs, PUT to replace, DELETE to remove) and listens on HTTP/HTTPS ports (typically 80/443 or the configured web-management ports), unlike NETCONF which runs over SSH. Option D is correct because the Junos REST API can return responses in JSON (as well as XML), which is a native capability of the REST interface, whereas NETCONF returns XML-encoded data. Option A is incorrect because TCP port 830 is the default NETCONF-over-SSH port, not a REST API port. Option B is incorrect because NETCONF does not require explicit SSH key pairs (password or key-based SSH both work), and the REST API does support encryption via HTTPS. Option E is incorrect because NETCONF over SSH maintains a persistent session, while REST is inherently stateless per HTTP request.

Answer

The REST API communicates directly over TCP port 830.

Answer

NETCONF requires explicit SSH key pairs for transport security, whereas REST API cannot use encryption.

Answer

NETCONF is stateless, whereas REST API maintains persistent interactive sessions by default.

Question 6

When developing Python scripts that utilize PyEZ and Jinja2, which THREE best practices ensure robust and maintainable automation code? (Choose three)

Accepted Answer

Using the PyEZ Config context manager to ensure locks are released and rollbacks occur on error. Option A is correct because the PyEZ Config context manager (with Config(dev) as cu:) automatically acquires the configuration lock, and on an exception it discards the candidate configuration and releases the lock, preventing stale locks and partial commits. Option C is correct because catching specific PyEZ exceptions such as ConnectError, ConfigError, LockError, and CommitError lets scripts handle connection and configuration failures precisely rather than masking all errors with a bare except. Option E is correct because keeping Jinja2 templates in separate .j2 files (loaded via Environment with FileSystemLoader) separates presentation from logic, improving readability, reuse, and maintainability. Option B is wrong because hardcoding administrative passwords in template files exposes credentials and violates secure secret-handling practices. Option D is wrong because omitting device.close() leaks NETCONF/SSH sessions and consumes device and client resources; sessions should be closed when work is complete.

Answer

Hardcoding administrative passwords inside template files for easy rendering

Answer

Avoiding device.close() calls to keep network sessions open permanently

Question 7

Which TWO Python standard library modules are commonly combined when a script needs to fetch web content (such as Junos REST API data) and parse the resulting payload? (Choose two)

Accepted Answer

json. Option D, urllib.request, is correct because it is the standard library module used to open URLs and perform HTTP requests, so it can fetch web content such as Junos REST API data. Option A, json, is correct because REST API payloads are typically returned in JSON format, and the json module parses that response text into Python dictionaries and lists. Together, urllib.request retrieves the raw response and json.loads() converts it into usable Python objects. Option B, yaml, is not needed here since the scenario specifies web content/REST payloads, which are JSON rather than YAML. Option C, socket, is a lower-level networking module and does not provide convenient HTTP fetching or payload parsing. Option E, pickle, is for serializing/deserializing Python objects and is not used to parse JSON API responses.

Answer

yaml

Answer

socket

Answer

pickle

Question 8

Which TWO components are essential parts of a model-driven network automation architecture on Junos devices? (Choose two)

Accepted Answer

YANG data models defining the structure and constraints of configuration and state data. Option A is correct because YANG data models are the foundational schema in a model-driven architecture, formally defining the structure, hierarchy, types, and constraints of both configuration and state data on Junos devices, enabling programmatic and vendor-neutral interaction. Option B is correct because model-driven automation requires standardized, model-aware management protocols — NETCONF (typically over SSH on port 830) and gRPC/gNMI — to transport YANG-modeled data and support operations like get-config, edit-config, and telemetry, rather than relying on human-readable CLI output. Options C, D, and E are not part of a model-driven architecture: Telnet terminal emulation, screen-scraping PERL scripts that parse raw CLI text, and physical serial port multiplexers all represent legacy, CLI-centric or hardware-centric approaches that lack structured data models and standardized programmatic interfaces.

Answer

Manual terminal emulation sessions using Telnet

Answer

Proprietary screen-scraping PERL scripts parsing raw CLI text

Answer

Physical serial port multiplexers

Question 9

An automation engineer is designing a Python script that converts Junos device configuration data between JSON and YAML formats. The script must correctly handle data types to avoid misconfiguration. Which TWO statements about JSON and YAML data type handling are correct? (Choose two.)

Accepted Answer

YAML represents a null value with the tilde (~) character.. YAML's tilde represents null, and YAML supports anchors and aliases for reuse. These features are absent in JSON, which lacks comments, disallows trailing commas, and requires escaped newlines for multi-line strings. Understanding these differences is essential when converting between formats in automation scripts.

Answer

JSON allows trailing commas in arrays and objects.

Answer

JSON natively supports multi-line strings without escaping newlines.

Answer

JSON supports comments, which can be used to annotate configuration sections.

Question 10

You are writing a Python script using PyEZ to retrieve and process operational data from a Junos device. Which TWO statements correctly describe the use of PyEZ Table and View for parsing operational data? (Choose two.)

Accepted Answer

A View defines how to extract specific fields from the XML response of an RPC.. A View defines the extraction of fields from XML, and a Table uses that View to parse RPC output into a list of dictionaries. The other statements are incorrect: Tables do not auto-convert to JSON, Views can be in Python, and Tables are for operational data.

Answer

Views must be defined in a separate YAML file and cannot be coded in Python.

Answer

Tables automatically convert all XML responses into JSON format.

Answer

Tables can only retrieve configuration data, not operational data.

Question 11

Which THREE tasks are typical responsibilities of a network DevOps engineer managing a Junos infrastructure? (Choose three)

Accepted Answer

Writing and maintaining Python automation scripts and Jinja2 templates. Option B is correct because a network DevOps engineer on Junos infrastructure typically writes Python automation scripts using libraries such as PyEZ and ncclient, and generates configuration from Jinja2 templates to push via NETCONF or Junos CLI, which is core to infrastructure-as-code. Option C is correct because managing Git repositories, branch policies, and pull request workflows is essential for version-controlling Junos configurations and enabling peer review and rollback. Option D is correct because configuring and maintaining CI/CD pipeline tools like GitLab CI or GitHub Actions automates validation, testing, and deployment of Junos configuration changes. Option A is not a DevOps responsibility since crimping CAT6 cables is a physical layer cabling task performed by cabling technicians, not automation engineers. Option E is not a DevOps responsibility because manually rebooting every switch daily is an operational anti-pattern that automation and proper monitoring would replace.

Answer

Manually crimping CAT6 Ethernet cables in the wiring closet

Answer

Manually rebooting every switch in the data center daily

Question 12

In a CI/CD pipeline configured for Junos network changes, which THREE automated testing steps are typically performed before production deployment? (Choose three)

Accepted Answer

Static code linting of YAML data and Jinja2 templates. Option C is correct because CI/CD pipelines for Junos automation typically begin with static code linting of YAML data files and Jinja2 templates to catch syntax errors, formatting issues, and template rendering problems before any configuration is pushed. Option D is correct because a dry-run candidate configuration validation on a test Junos device or virtual instance (e.g., using 'commit check' or 'load merge' in a lab/vSRX/vMX environment) verifies that the generated configuration is syntactically and semantically accepted by Junos without affecting production. Option E is correct because automated schema validation against YANG models ensures the intended configuration data conforms to the device's data model, catching invalid leaf values, wrong types, or unsupported nodes early in the pipeline. Option A is not a testing step but a physical hardware maintenance action, and Option B is a manual human process unrelated to automated CI/CD validation, so neither belongs in an automated pre-deployment test suite.

Answer

Physical replacement of router power supply units

Answer

Manual approval of physical fiber patch cables by a security guard

Question 13

Which TWO of the following are valid extensions commonly used for YAML files? (Choose two)

Accepted Answer

.yaml. Option C (.yaml) is correct because .yaml is the canonical, officially recommended file extension for YAML documents, as defined by the YAML specification and used by tools like PyYAML, Kubernetes manifests, and Ansible playbooks. Option E (.yml) is also correct because .yml is the widely accepted short-form alternative extension for YAML files, supported by virtually all YAML parsers and commonly seen in CI/CD configs such as .travis.yml, docker-compose.yml, and GitHub Actions workflows. Option A (.xml) is incorrect because it denotes Extensible Markup Language files, a completely different markup syntax with angle-bracket tags, not YAML's indentation-based structure. Option B (.jsn) is incorrect because it is not a standard extension for any common serialization format; JSON files use .json, and .jsn is not a recognized YAML extension. Option D (.txt) is incorrect because plain-text files have no defined structure and are not parsed as YAML by convention, even though YAML is technically a text format.

Answer

.xml

Answer

.jsn

Answer

.txt

Question 14

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 15

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. Option B is correct because feature branches isolate new Junos configuration changes from the main branch, allowing development and validation without destabilizing production-ready configurations before a controlled merge. Option D is correct because peer reviews and pull request approvals enforce a four-eyes principle, catching errors, policy violations, or unintended commit/rollback commands before changes reach the main branch. Option E is correct because semantic or descriptive commit messages document the intent of each configuration update, which is essential for audit trails, troubleshooting, and correlating commits with change tickets in Junos automation workflows. Option A does not belong because bypassing automated testing removes validation of syntax, commit checks, and rollback safety, increasing outage risk. Option C does not belong because storing plaintext administrative passwords in public Git repositories exposes credentials and violates security best practices; secrets should be managed with tools like Ansible Vault, HashiCorp Vault, or Junos encrypted passwords.

Answer

Completely bypassing automated testing to speed up deployments

Answer

Storing plaintext administrative passwords directly in public Git repositories

Question 16

In Git version control, which TWO commands are used to integrate changes from one branch into another? (Choose two)

Accepted Answer

git merge. git merge (B) is correct because it integrates changes from one branch into another by combining their commit histories, typically creating a merge commit when the target branch has diverged. git rebase (E) is also correct because it integrates changes by replaying commits from one branch onto another, producing a linear history. git init (A) only initializes a new repository and does not integrate branch changes. git status (C) merely reports working tree and staging state without modifying history. git clone (D) copies a remote repository locally but does not merge or rebase branches.

Answer

git init

Answer

git status

Answer

git clone

Question 17

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. Option B, separators, is correct because json.dumps() accepts a (item_separator, key_separator) tuple that controls the characters placed between JSON elements, letting you produce compact output such as (',', ':') for smaller Junos payloads. Option C, sort_keys, is correct because setting sort_keys=True makes json.dumps() emit object keys in sorted order, which yields deterministic, diff-friendly JSON for configuration and automation scripts. Option E, indent, is correct because passing indent (for example indent=2 or indent=4) pretty-prints the JSON with newlines and that many spaces per level, improving readability of Junos payloads. Option A, max_depth, is not a valid json.dumps() parameter; Python's json module has no depth-limiting argument. Option D, strict_mode, is also not a json.dumps() parameter; the closest real argument is strict, which controls whether control characters inside strings are allowed, but 'strict_mode' itself does not exist.

Answer

max_depth

Answer

strict_mode

Question 18

In a Junos NETCONF automation workflow, what happens during a lock operation on the configuration database? (Choose two)

Accepted Answer

Exclusive write access is acquired for the requesting session, preventing concurrent configuration modifications by other users or scripts.. Option A is correct because a Junos operation on the candidate configuration grants the requesting NETCONF session exclusive write access, so other users, CLI sessions, or automation scripts cannot modify the configuration concurrently until the lock is released. Option C is correct because the lock is held by that session and must be explicitly released with an operation, or implicitly released when the NETCONF session closes, before other processes can edit the configuration. The unmarked options are incorrect: B is false because locking the configuration database has nothing to do with powering down a Routing Engine, D is false because operational commands like 'show route' remain available and are not disabled by a configuration lock, and E is false because no firewall filters are deleted by a lock operation.

Answer

The physical routing engine is immediately powered down to prevent hardware wear.

Answer

All operational state monitoring (such as 'show route') is permanently disabled.

Answer

All firewall filters on all interfaces are automatically deleted.

Question 19

Which TWO tools or platforms are commonly used for version control and hosting of Junos automation code repositories? (Choose two)

Accepted Answer

GitHub. GitHub (C) is correct because it is a widely used web-based platform built on Git that provides repository hosting, branching, pull requests, and CI/CD integration for storing and collaborating on Junos automation code such as Python scripts, Jinja2 templates, and YAML playbooks. GitLab (E) is also correct because it is a Git-based DevOps platform offering self-managed or SaaS repository hosting, merge requests, and built-in CI/CD pipelines commonly used to manage and deploy Junos automation content. The remaining options do not belong: Adobe Photoshop (A) is an image-editing application, Microsoft Word (B) is a document word processor, and VLC Media Player (D) is a multimedia player — none of these provide Git-based version control or code repository hosting.

Answer

Adobe Photoshop

Answer

Microsoft Word

Answer

VLC Media Player

Question 20

Which THREE mechanisms are valid methods for authenticating and establishing a NETCONF session with a Junos device? (Choose three)

Accepted Answer

Remote RADIUS or TACACS+ AAA server integration via SSH transport. Option B is correct because NETCONF sessions are established over SSH (default TCP port 830), and the client can authenticate with a username and password just like a standard SSH login. Option C is correct because SSH public key authentication is a supported method for authenticating the NETCONF-over-SSH session, using the client's private key matched against an authorized key on the Junos device. Option A is correct because Junos can delegate authentication of NETCONF-over-SSH users to external RADIUS or TACACS+ AAA servers, so credentials are validated by the remote AAA server rather than only local accounts. Option D is wrong because NETCONF requires authenticated credentials and does not permit anonymous guest access. Option E is wrong because NETCONF uses SSH transport, not unencrypted cleartext Telnet on TCP port 23.

Answer

Anonymous guest access without credentials

Answer

Unencrypted cleartext Telnet on TCP port 23