JNCIA-DevOps Junos REST API Practice Test 5 — 15 Questions

Question 1

Which THREE advantages are associated with using the Junos REST API over NETCONF in lightweight automation scripts? (Choose three)

Accepted Answer

Ability to traverse standard HTTP/HTTPS proxies and load balancers easily.. Option A is correct because the Junos REST API communicates over standard HTTP/HTTPS, so it traverses corporate proxies, firewalls, and load balancers using well-understood ports (80/443) without the SSH-based NETCONF transport complications. Option B is correct because REST responses can be returned in native JSON, letting lightweight scripts use built-in JSON parsers instead of requiring XML libraries such as lxml that NETCONF's XML payloads demand. Option C is correct because the REST API maps operations to familiar HTTP verbs (GET for retrieval, POST for creation/RPCs, PUT for replacement, DELETE for removal), aligning with common web development patterns and tooling. Option D is not correct because the Junos REST API still operates against the Junos configuration datastores, including the candidate configuration, so it does not eliminate them. Option E is not correct because transaction rollback is a Junos commit feature tied to Junos devices, and the REST API provides no guaranteed multi-vendor rollback across non-Juniper hardware.

Answer

Elimination of the Junos candidate configuration datastore.

Answer

Guaranteed multi-vendor transaction rollbacks across non-Juniper hardware.

Question 2

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 3

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 4

An automation developer is writing a script to modify candidate configuration data on a Junos device using the REST API. Which HTTP method and request body format should be used to replace an existing configuration hierarchy?

Accepted Answer

PUT method with a JSON or XML payload representing the configuration node. The Junos REST API uses standard HTTP methods mapped to NETCONF-like operations: PUT replaces an existing configuration hierarchy at the specified URL with the payload provided (JSON or XML). To replace a configuration node, you send a PUT to the configuration endpoint with the new hierarchy in the body. POST is used to create/merge, DELETE to remove, and GET to retrieve.

Answer

POST method with form-urlencoded data

Answer

DELETE method with an empty body

Answer

GET method with URL parameters

Question 5

An engineer needs to retrieve the entire candidate configuration in JSON format from a Junos device using the Junos REST API. Which HTTP header must be included in the GET request to ensure the response is returned in JSON format?

Accepted Answer

Accept: application/json. The Accept header with 'application/json' specifies that the client expects the response to be formatted in JSON.

Answer

Transfer-Encoding: chunked

Answer

Content-Type: text/xml

Answer

X-Junos-Data-Format: json

Question 6

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 7

Which TWO benefits are gained by using the Junos REST API instead of traditional CLI screen-scraping in automation workflows? (Choose two)

Accepted Answer

Structured data formats (JSON or XML) eliminate the need for complex regular expression parsing of CLI text.. Option B is correct because the Junos REST API returns responses in structured formats such as JSON or XML, so automation code can parse fields directly instead of relying on fragile regular expressions to extract values from human-oriented CLI text. Option E is correct because REST API calls return standard HTTP status codes (for example 200 for success, 400 for a bad request, 401 for authentication failure) plus structured error payloads, giving automation workflows explicit, programmatic error handling that screen-scraping cannot provide. Option A is incorrect because screen-scraping typically consumes more routing-engine CPU and is less efficient than the REST API, not less. Option C is incorrect because screen-scraping is generally slower and more brittle for bulk configuration pushes than the REST API. Option D is incorrect because the Junos REST API still requires authentication configuration, such as user credentials or an access token, on the device.

Answer

CLI screen-scraping uses less CPU on the Junos routing engine than REST API.

Answer

Screen-scraping is faster than REST API for bulk configuration pushes.

Answer

REST API requires no authentication configuration on the device.

Question 8

An automation engineer is writing a Python script that retrieves the operational status of all interfaces from a Junos device using the Junos REST API. The script sends a GET request to https://device/rest/interface. The device returns an HTTP 200 OK response, but the response body is empty. The engineer examines the request and confirms that the URL is correct and the device is reachable. Which action should the engineer take to retrieve the interface status information?

Accepted Answer

Use the correct RPC endpoint, such as /rest/rpc/get-interface-information, to retrieve operational data.. The Junos REST API provides access to operational data through RPCs, not through arbitrary REST endpoints. To retrieve interface status, the correct endpoint is /rest/rpc/get-interface-information. A GET request to /rest/interface does not correspond to a valid RPC and returns an empty body. Using the proper RPC endpoint ensures the desired operational information is returned in the response.

Answer

Add the Accept: application/json header to the request.

Answer

Change the HTTP method to POST and include a JSON payload specifying the interface names.

Answer

Append the query parameter ?type=operational to the URL.

Question 9

An automation engineer needs to retrieve the operational status of all interfaces from a Junos device using the Junos REST API over HTTPS. The device is configured with the REST API enabled and the engineer has valid credentials. Which HTTP request accomplishes this task?

Accepted Answer

GET https://<device>/rest/interface-information. The Junos REST API exposes operational RPCs under the /rest/ URI path. To retrieve interface operational status, an automation tool sends a GET request to /rest/interface-information. GET is the correct HTTP method for read-only retrieval, and no additional parameters are needed for a full interface listing. Other paths like /rpc/ belong to the XML API, and using POST for retrieval is incorrect.

Answer

POST https://<device>/rest/interface-information

Answer

GET https://<device>/rest/conf/show-interfaces

Answer

POST https://<device>/rpc/get-interface-information

Question 10

A network automation team is using the Junos REST API to manage configurations on a fleet of Junos devices. They need to ensure that configuration changes are applied atomically and that they can roll back if an error occurs. They decide to use the REST API to load a configuration, commit it, and then verify the commit. Which sequence of REST API calls should they use to load a configuration snippet, commit it, and then confirm the commit was successful?

Accepted Answer

POST to /rest/rpc/load-configuration with the configuration data, then POST to /rest/rpc/commit, then check the HTTP status code and response body of the commit call for success indicators. To load, commit, and verify a configuration via the Junos REST API, you perform a POST to the load-configuration RPC with the configuration data, then a POST to the commit RPC. The commit response includes an HTTP status code and a body that indicates success or failure. Checking this response is the most direct way to confirm the commit succeeded. Additional calls like get-configuration or get-commit-information are not necessary for verifying the commit operation itself.

Answer

POST to /rest/rpc/load-configuration with the configuration data, then POST to /rest/rpc/commit, then GET /rest/rpc/get-configuration to verify the applied configuration

Answer

POST to /rest/rpc/load-configuration, then POST to /rest/rpc/commit, then GET /rest/rpc/get-commit-information

Answer

POST to /rest/rpc/load-configuration, then POST to /rest/rpc/commit-check, then POST to /rest/rpc/commit

Question 11

A network automation developer is writing a Python script that uses the Junos REST API to load a candidate configuration from a file and commit it. The developer wants to ensure the configuration is merged with the existing candidate configuration. Which HTTP method and endpoint should be used to load the configuration?

Accepted Answer

POST to /rest/conf/ with the configuration in the request body. To load configuration into the candidate configuration via the Junos REST API, an automation script sends an HTTP POST request to the /rest/conf/ endpoint with the configuration data in the request body. This operation defaults to a merge load, combining the new configuration with the existing candidate. Other methods like PUT or GET are not used for configuration loading.

Answer

GET to /rest/conf/ with the configuration as a query parameter

Answer

POST to /rest/config/ with the configuration in the request body

Answer

PUT to /rest/conf/ with the configuration in the request body

Question 12

An automation engineer is troubleshooting a Junos REST API script that intermittently fails with HTTP 401 Unauthorized errors when retrieving operational data. The script uses HTTP Basic Authentication with a valid username and password. The engineer confirms that the credentials are correct and that the REST API is enabled. What is the most likely cause of the intermittent failures?

Accepted Answer

The device is configured to use RADIUS authentication, and the RADIUS server is occasionally unreachable.. Intermittent 401 Unauthorized errors with valid credentials often stem from external authentication server issues. When a Junos device is configured to use RADIUS or TACACS+ for user authentication, temporary server unreachability can cause authentication failures. The REST API uses the device's configured authentication methods, so an unreachable RADIUS server would result in 401 responses.

Answer

The script is exceeding the maximum number of concurrent REST API sessions, causing new requests to be rejected with 401.

Answer

The device's clock is out of sync with the authentication server, causing token-based authentication to fail.

Answer

The REST API requires the use of a session cookie instead of Basic Authentication for operational requests.

Question 13

An automation engineer is tasked with implementing a REST API client that authenticates to a Junos device. The engineer must choose an authentication method supported by the Junos REST API and ensure that credentials are transmitted securely. Which two statements are correct about authentication for the Junos REST API? (Choose two.)

Accepted Answer

Authentication can be performed using a session cookie obtained from a login RPC.. The Junos REST API supports HTTP Basic Authentication, where credentials are base64-encoded and sent in the Authorization header. It also supports session-based authentication via a login RPC that returns a cookie. Both methods require HTTPS for secure transmission. OAuth 2.0 and API keys are not natively supported. Credentials are not sent in plain text by default; base64 encoding is not encryption, so HTTPS is essential.

Answer

API keys generated on the Junos device can be used in place of passwords.

Answer

Credentials are sent in plain text by default, so HTTPS is optional.

Answer

OAuth 2.0 tokens are natively supported for authentication.

Question 14

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 15

A network automation team is using the Junos REST API to manage configurations on a Junos device. They need to perform a commit operation that includes a commit comment and also synchronizes the commit across all Routing Engines in a dual-RE system. Which HTTP method and URI combination should they use to achieve this with a single request?

Accepted Answer

POST to /rpc/commit with an XML body including and . To execute a commit with a comment and synchronization, the Junos REST API requires a POST request to /rpc/commit with an XML body containing the and elements. This leverages the RPC mechanism, allowing multiple commit options in one request. Other methods and endpoints do not support this functionality.

Answer

POST to /rpc/commit with a JSON body containing and

Answer

PUT to /config/commit with a JSON body specifying comment and synchronize

Answer

PATCH to /rpc/commit with a JSON body containing comment and synchronize attributes