JNCIA-DevOps Practice Test 17 — 15 Questions

Question 1

You are using PyEZ to retrieve the operational status of all interfaces on a Junos device. You want to get the output in a structured Python dictionary rather than raw XML. Which method should you use on the Device object?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

`dev.rpc.get_interface_information(normalize=True)`. To get structured dictionary output from an RPC in PyEZ, use the `normalize=True` parameter. This converts the XML response into a Python dictionary. Other methods either return XML, facts, or raw text, and do not provide the interface status as a dictionary.

Answer

`dev.facts`

Answer

`dev.rpc.get_interface_information()`

Answer

`dev.cli('show interfaces')`

Question 2

You are automating the retrieval of operational data from a Junos device using PyEZ. You write a Python script that calls the RPC method `get_interface_information` with the argument `terse=True` on a `Device` object. The script executes successfully, but the returned XML contains only a subset of interface details, missing fields like `admin-status` and `oper-status`. You need the full operational status for each interface. What should you do to obtain the complete data?

Accepted Answer

Remove the `terse=True` argument from the RPC call to retrieve the full interface information.. The `terse` argument is a common RPC option that reduces output size by omitting detailed fields. For complete operational status, it must be omitted. The other options either retrieve the wrong type of data or do not affect the output completeness. Removing `terse=True` directly addresses the missing fields.

Answer

Use the `get_config` method with `config_format='set'` to retrieve the interface configuration and infer the operational status.

Answer

Set the `normalize=True` parameter in the `Device` object to ensure all fields are returned.

Answer

Call `get_interface_information` with `interface_name='all'` to retrieve details for every interface including all status fields.

Question 3

When troubleshooting REST API authentication and authorization on Junos devices, which THREE log files or diagnostic tools can an administrator inspect? (Choose three)

Accepted Answer

HTTP response headers and status codes returned by the API client.. Option B is correct because the HTTP response headers and status codes returned by the API client directly reveal REST API authentication and authorization outcomes, such as 401 Unauthorized for failed authentication or 403 Forbidden for insufficient privileges, making them a primary diagnostic tool. Option C is correct because the jpagent process handles Junos REST API requests, and enabling traceoptions under system services jpagent writes detailed request, authentication, and authorization handling information to the jpagent trace log for inspection. Option E is correct because /var/log/messages records daemon startup and authentication-related events, including messages from processes involved in REST API access, which helps correlate login and service failures. Option A is not relevant because kernel core dumps in /var/crash/kernel capture kernel crash data, not REST API authentication or authorization activity. Option D is not relevant because BGP peer state packet captures in Wireshark analyze routing protocol behavior, not REST API authentication or authorization flows.

Answer

Kernel core dump files located in /var/crash/kernel.

Answer

BGP peer state packet captures in Wireshark.

Question 4

Which TWO statements are true regarding PyEZ Table and View definitions? (Choose two)

Accepted Answer

A View defines how individual fields within the returned XML elements are mapped to Python dictionary keys.. Option C is correct because a PyEZ View specifies the mapping between fields in the returned XML (via XPath expressions) and the corresponding Python dictionary keys, allowing structured access to the data. Option D is correct because PyEZ Tables are commonly defined in YAML files, where you declare the table's XPath, view, and key/column mappings. Option A is wrong because Tables are primarily used to retrieve and parse operational state, not to modify configuration. Option B is wrong because Tables parse XML directly using their View definitions; Jinja2 templates are used for configuration templating, not for Table parsing. Option E is wrong because a View is only a schema/mapping definition and still requires a Device object (or an equivalent connection) to fetch data from the device.

Answer

Tables can only be used to modify device configurations, not read operational state.

Answer

Tables require Jinja2 templates to parse raw XML output.

Answer

Views replace the need to instantiate a Device object.

Question 5

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 6

An enterprise network is adopting a CI/CD pipeline for Junos network changes using GitLab CI. A developer wants to ensure that a test job automatically runs whenever a merge request is opened against the main branch. In which configuration file must this pipeline behavior be defined, and what is the primary keyword used to control branch execution?

Accepted Answer

.gitlab-ci.yml, using the 'rules' or 'only' keyword. GitLab CI pipelines are defined in a .gitlab-ci.yml file located in the root of the repository, and jobs use the 'rules' or 'only/except' keywords to control execution on specific branches.

Answer

Junos 'juniper.conf', using the 'commit-script' keyword

Answer

ansible.cfg, using the 'hosts' parameter

Answer

Jenkinsfile, using the 'when' parameter

Question 7

Which of the following primitive data types is NOT supported natively in JSON?

Accepted Answer

Undefined. JSON supports a limited set of primitive data types defined in RFC 8259: string, number, boolean, null, object, and array. 'Undefined' is not one of them — it is a JavaScript-specific value that has no representation in the JSON specification. When JavaScript serializes an object with JSON.stringify(), any property whose value is undefined is simply omitted from the output rather than encoded.

Answer

Number

Answer

String

Answer

Null

Question 8

An engineer is comparing how NETCONF and the Junos REST API handle candidate configuration validation. In NETCONF, the client can issue a <validate> RPC. How is configuration validation typically handled in the Junos REST API workflow?

Accepted Answer

Configuration updates via REST API can include validation parameters or commit-check actions to verify syntax before finalizing.. The Junos REST API supports validation parameters or actions (such as checking candidate syntax during configuration updates or invoking validation actions via commit parameters) to ensure correctness before committing.

Answer

NETCONF validates via XML, while REST API automatically converts invalid syntax into comments.

Answer

Validation requires downloading the entire configuration as a text file and running an external Python syntax checker.

Answer

Validation is impossible in REST API; changes are always applied directly to the forwarding plane immediately.

Question 9

Which TWO benefits are provided by implementing automated CI/CD pipelines for Junos network changes? (Choose two)

Accepted Answer

Standardized, repeatable validation and testing of every change before production. Option A is correct because CI/CD pipelines run standardized, repeatable validation and testing (e.g., Junos commit check, configuration linting, and automated test suites) on every proposed change before it reaches production, ensuring consistency and catching errors early. Option D is correct because automation accelerates deployment by pushing validated configurations rapidly and consistently, removing manual CLI typing and thereby reducing human configuration errors. Option B is incorrect because CI/CD automation does not eliminate routing protocols such as OSPF; those protocols remain essential for dynamic routing regardless of how changes are deployed. Option C is incorrect because automated pipelines handle software and configuration changes, not physical hardware replacement like swapping optical transceivers, which still requires human or robotic intervention outside CI/CD scope. Option E is incorrect because no pipeline can guarantee 100% uptime; fiber cuts are physical-layer failures that CI/CD cannot prevent.

Answer

Elimination of network routing protocols like OSPF

Answer

Immediate physical replacement of broken optical transceivers by robots

Answer

Guaranteed 100% uptime regardless of fiber cuts

Question 10

An automation team is designing a script that uses the Junos REST API to manage configurations on a fleet of Junos devices. They need to ensure secure communication and proper error handling. Which two practices should they implement? (Choose two.)

Accepted Answer

Parse HTTP status codes and response bodies to detect and handle API errors gracefully.. Secure automation with the Junos REST API requires using HTTPS with certificate validation to protect data in transit and verify the device. Additionally, robust error handling by checking HTTP status codes and parsing response bodies ensures the script can detect and respond to failures. These practices together provide security and reliability.

Answer

Store credentials in plaintext within the script to avoid external dependencies.

Answer

Disable SSL certificate verification in the script to prevent connection failures due to self-signed certificates.

Answer

Use HTTP instead of HTTPS to reduce latency and simplify certificate management.

Question 11

Which TWO characters or sequences are valid in YAML for representing lists or sequences? (Choose two)

Accepted Answer

Hyphen followed by a space (- ). Option A is correct because YAML uses a hyphen followed by a space ("- ") as block sequence indicator, where each list item is introduced by that dash at the same indentation level. Option E is correct because YAML supports flow sequences written with square brackets, e.g. [one, two, three], representing a list inline. Option B is incorrect because a semicolon followed by a space is not a YAML list indicator; semicolons are not used for sequences in YAML. Option C is incorrect because angle brackets are not YAML sequence syntax; they are used in other markup languages or as plain scalar characters. Option D is incorrect because curly braces denote flow mappings (key-value pairs), not sequences.

Answer

Semicolon followed by a space (; )

Answer

Angle brackets (< >)

Answer

Curly braces ({ })

Question 12

When converting a deeply nested JSON data structure representing Junos device health metrics into YAML using PyYAML, the output uses complex block styles that are difficult for team members to read. Which parameter in yaml.safe_dump() can force scalar values or containers to prefer flow style (JSON-like curly braces and brackets) instead?

Accepted Answer

default_flow_style=True. The default_flow_style parameter in yaml.safe_dump() controls whether containers (lists and dictionaries) are rendered in flow style (JSON-like with braces and brackets) or block style (indented). Setting default_flow_style=True forces all containers to use flow style, making the output more compact and JSON-like. This directly addresses the readability issue caused by complex block styles.

Answer

force_json=True

Answer

format='compact'

Answer

style='flow'

Question 13

When comparing the Junos REST API workflow to the NETCONF protocol workflow, which characteristic is unique to the REST API?

Accepted Answer

It requires the use of HTTP verbs such as GET, POST, PUT, and DELETE.. The Junos REST API uniquely requires the use of HTTP verbs such as GET, POST, PUT, and DELETE to perform operations. This is a fundamental characteristic of RESTful APIs, distinguishing it from NETCONF, which uses XML-based RPCs over SSH. NETCONF does not use HTTP verbs; it uses <rpc> elements within a NETCONF session.

Answer

It exclusively transmits data encoded in protocol buffers.

Answer

It uses connection-oriented stateful sessions over port 830.

Answer

It mandates the use of YANG schema files for every single RPC.

Question 14

An automation engineer is writing a Python script to parse a Juniper Junos NETCONF reply received in XML format and needs to convert it into a JSON structure for easier manipulation in a web application. Which built-in Python module is primarily used to handle JSON data serialization and deserialization?

Accepted Answer

json. The 'json' module is the standard built-in Python library used for parsing, serializing, and deserializing JSON data.

Answer

pickle

Answer

yaml

Answer

xml.etree

Question 15

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.

Answer

To prevent Jinja2 rendering engines from running out of memory.

Answer

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