JNCIA-DevOps Junos REST API — 40 Questions

Question 1

An administrator wishes to secure their Junos REST API connections by configuring HTTPS instead of plain HTTP. Which command under 'system services jpagent' accomplishes this?

Accepted Answer

set system services jpagent https. To enable HTTPS for the Junos REST API agent, the administrator must configure the 'https' option under 'set system services jpagent'.

Answer

set system services netconf ssl

Answer

set security ipsec-vpn

Answer

set system services rest secure

Question 2

Which service daemon must be explicitly enabled in the Junos CLI configuration to allow REST API requests to be processed by the routing engine?

Accepted Answer

set system services jpagent. The Junos REST API is managed by the 'jpagent' (Junos Plugin Agent) service. It must be enabled under the 'system services' hierarchy for REST API requests to function.

Answer

set system services api-daemon

Answer

set system services netconf

Answer

set system services rest http

Question 3

An automation engineer is trying to retrieve operational data from a Junos device using the REST API. They send an HTTP GET request to the URI path 'http://192.168.1.1:3000/api/font/operational/system/information', but the request fails with a 404 Not Found error. What is the cause of this failure?

Accepted Answer

The URI path contains an invalid prefix segment 'font' instead of the required API root structure.. The correct base path for Junos REST API operational data uses 'rpc' or 'initial' or specific resource endpoints like /api/restful/rit/rpc, but the standard path prefix for RPCs and operational data via the Junos REST API begins with /api/operational/ rather than /api/font/operational/.

Answer

Authentication credentials were missing from the HTTP header.

Answer

The port 3000 is reserved for NETCONF and cannot be used for REST API requests.

Answer

Operational data retrieval requires an HTTP POST method instead of GET.

Question 4

When comparing NETCONF and the Junos REST API workflows, which statement accurately describes how configuration locks are handled?

Accepted Answer

NETCONF requires explicit lock and unlock commands, whereas REST API transactions typically manage locks implicitly during request execution.. NETCONF explicitly requires lock and unlock operations on configuration datastores (candidate/running). The Junos REST API abstracts state management or handles implicit locking depending on the specific API call, whereas NETCONF leaves lock management entirely to the client's explicit RPC control.

Answer

Neither protocol utilizes locking mechanisms since Junos uses optimistic concurrency control.

Answer

The Junos REST API enforces exclusive global locking which prevents any concurrent NETCONF sessions.

Answer

Both NETCONF and Junos REST API require the client to manually issue an explicit lock RPC before making changes.

Question 5

An engineer needs to modify a configuration parameter using the Junos REST API via an HTTP PUT request. They include the Content-Type header as 'application/json'. However, the device rejects the payload. What is the correct Content-Type or Accept header requirement for configuration manipulation payload representation in Junos REST API?

Accepted Answer

application/vnd.juniper.netconf.config+json. Junos REST API supports both JSON and XML representations. When sending configuration payloads, the Content-Type must match the format being transmitted, such as application/vnd.juniper.netconf.config+json or application/json depending on the API version, but application/vnd.juniper.netconf.config+json is specifically designed for structural configuration mapping.

Answer

application/x-www-form-urlencoded

Answer

text/xml only

Answer

multipart/form-data

Question 6

How does the Junos REST API handle configuration commits compared to NETCONF workflow behavior?

Accepted Answer

NETCONF utilizes explicit lock, candidate modification, and commit RPC workflows, while REST API provides resource-based endpoints where configuration changes can trigger auto-commits or be committed via dedicated commit URIs.. In NETCONF, changes are made to the candidate datastore and must be explicitly committed using the <commit> RPC. In the Junos REST API, configuration changes made via PUT, POST, or DELETE can either auto-commit depending on the API call parameters or require a separate commit action, but unlike NETCONF's explicit candidate/running model, REST abstracts transactions into resource endpoints where commit behaviors are managed via query parameters or dedicated commit endpoints.

Answer

REST API does not support committing configurations; it is strictly read-only for operational data.

Answer

NETCONF requires an explicit <commit> RPC, whereas the Junos REST API executes modifications directly against the running configuration with optional commit flags.

Answer

Both protocols bypass the candidate datastore entirely and write directly to NVRAM.

Question 7

An automation engineer needs to check if the Junos REST API is actively running and responsive on a managed device without querying heavy configuration data. Which lightweight endpoint can be queried?

Accepted Answer

/api/initial. The Junos REST API provides an initial or root status endpoint, often /api/initial or root discovery endpoints, to verify service availability and root resource links.

Answer

/healthz

Answer

/api/v1/system/ping

Answer

/status/ping

Question 8

An administrator wants to retrieve the configuration of a specific interface (e.g., ge-0/0/0) using the Junos REST API. Which URI structure is appropriate for fetching this configuration resource in JSON format?

Accepted Answer

/api/configuraton/interfaces/interface/name/ge-0/0/0. The Junos REST API uses structured paths matching the configuration hierarchy, typically prefixed by /api/configuraton/interfaces/interface/ge-0/0/0 or similar resource roots depending on the Junos release.

Answer

/rpc/get-config?interface=ge-0/0/0

Answer

/netconf?subsystem=ge-0/0/0

Answer

/api/operational/interfaces/ge-0/0/0

Question 9

When configuring the Junos REST API, an administrator restricts access to a specific port and enables SSL. Which configuration statement sets the secure HTTPS port to 8443?

Accepted Answer

set system services jpagent https port 8443. To customize the HTTPS port for the jpagent service in Junos, the administrator uses the 'set system services jpagent https port 8443' command.

Answer

set protocols rest-api https port 8443

Answer

set system services rest port 8443 secure

Answer

set system services netconf https-port 8443

Question 10

What is the default TCP port used by the Junos jpagent for unencrypted HTTP REST API connections?

Accepted Answer

3000. The Junos REST API daemon (jpagent) listens on TCP port 3000 by default for HTTP traffic, and port 3443 for HTTPS traffic.

Answer

80

Answer

830

Answer

8080

Question 11

An administrator wants to disable the Junos REST API daemon entirely. Which CLI command achieves this?

Accepted Answer

delete system services jpagent. To disable the jpagent service, the administrator uses the 'delete system services jpagent' command in configuration mode.

Answer

deactivate protocols rest-api

Answer

set system services jpagent disable

Answer

stop system services rest

Question 12

When sending an HTTP POST request to create a new configuration resource via the Junos REST API, what happens if the resource already exists in the candidate configuration?

Accepted Answer

The request is rejected, typically returning a 409 Conflict status code.. In standard REST semantics and Junos REST implementation, a POST request to an existing resource may result in a conflict error (such as HTTP 409 Conflict) or duplicate creation error if the identifier already exists, whereas PUT is idempotent and overwrites.

Answer

The device automatically performs an HTTP DELETE followed by a POST.

Answer

The device silently ignores the request and returns 200 OK.

Answer

The existing resource is converted to an operational state counter.

Question 13

When comparing the workflow and capabilities of the Junos REST API versus NETCONF, which THREE statements are correct? (Choose three)

Accepted Answer

NETCONF requires explicit and RPC workflows, whereas REST API abstracts transaction locking implicitly.. Option A is correct because NETCONF's candidate datastore workflow requires the client to issue explicit and RPCs (or / equivalents) to prevent concurrent edits, whereas the Junos REST API hides this transaction locking behind its HTTP request handling, so callers do not manage locks manually. Option C is correct because NETCONF runs as an SSH subsystem on TCP port 830 (per RFC 6242), while the Junos REST API is exposed over HTTP/HTTPS (typically ports 80/443, or 8080/8443 in some configurations) using REST-style URLs. Option E is correct because both interfaces can retrieve and modify the Junos configuration database and can also execute operational commands against the operational (state) database, for example via NETCONF / and REST API configuration/operational endpoints. Option B is incorrect because the Junos REST API supports both JSON and XML payloads, and NETCONF uses XML-encoded messages over SSH, not binary streams. Option D is incorrect because NETCONF fully supports commit operations via the RPC (including confirmed commit), and the REST API does not auto-commit every keystroke; changes are committed explicitly through a commit request.

Answer

Junos REST API only supports JSON format, while NETCONF only supports binary streams.

Answer

NETCONF does not support commit operations, whereas REST API automatically commits every keystroke.

Question 14

Which TWO configuration steps are required to enable the Junos REST API with basic security settings? (Choose two)

Accepted Answer

set system services jpagent https. Option B is correct because the Junos REST API is provided by the jpagent (Juniper Web Agent) service, and enabling it over HTTPS requires the configuration statement 'set system services jpagent https', which turns on the REST API listener on TCP port 443. Option D is also correct because 'set system services jpagent' is the prerequisite statement that enables the jpagent service itself; without it, the HTTPS sub-statement alone would not activate the REST API. Option A is incorrect because 'set system netconf secure-mode' relates to securing the NETCONF over SSH service, not the REST API. Option C is incorrect because 'set protocols rest-api state active' is not valid Junos syntax for enabling the REST API. Option E is incorrect because 'set system services rest enable' is not a valid Junos command; the REST API is enabled through the jpagent service, not a 'rest' service.

Answer

set system netconf secure-mode

Answer

set protocols rest-api state active

Answer

set system services rest enable

Question 15

When troubleshooting Junos REST API integration issues, which THREE factors should an engineer examine if API requests return connection timeouts or refused errors? (Choose three)

Accepted Answer

Whether firewall filters or security zones permit traffic to TCP port 3000 or 3443.. Connection timeouts or refused errors point to reachability or service-listening problems, so the engineer should first verify network reachability and IP connectivity between the client and the Junos management interface (fxp0 or RE loopback) (C), since a routing, ARP, or interface issue will prevent any TCP handshake. Next, firewall filters or security zones must permit traffic to TCP port 3000 (HTTP) or 3443 (HTTPS) used by the Junos REST API (A); a blocked port produces exactly the timeout/refused symptom. Finally, the jpagent service (D) is the Junos process that hosts the REST API, so it must be configured and active (show services jpagent status) or the RE will refuse connections even when reachable. BGP routing to external peers (B) is irrelevant because REST API access is to the local management interface, not an external BGP peer, and the NETCONF subsystem script (E) concerns the NETCONF/XML API over SSH, not the REST API's HTTP/HTTPS transport.

Answer

Whether the BGP routing table has valid routes to external BGP peers.

Answer

Whether the NETCONF subsystem script is properly compiled in Python 2.7.

Question 16

An engineer is designing an automated failover script that needs to discard candidate configuration changes made via the Junos REST API. How should this discard action be performed?

Accepted Answer

Send a request to the configuration discard/rollback endpoint or invoke the discard-changes RPC via the REST API.. To discard candidate configuration changes via the Junos REST API, you must send a request to the configuration discard/rollback endpoint or invoke the discard-changes RPC. The REST API provides a specific endpoint for this action, typically a POST to /api/configuration/discard or using the 'discard-changes' RPC. This is the correct way to revert uncommitted changes.

Answer

Send an HTTP GET request with ?action=reset.

Answer

Issue an HTTP DELETE request to the root /api/configuration path.

Answer

Restart the routing engine process (RE switchover).

Question 17

Which Junos configuration command enables the REST API daemon to start automatically upon device boot?

Accepted Answer

set system services jpagent. Enabling any system service like jpagent under 'set system services jpagent' ensures it starts automatically upon device boot and initialization.

Answer

set chassis auto-restart jpagent

Answer

set management daemon jpagent start

Answer

set system boot-services rest

Question 18

When configuring advanced options for the Junos REST API jpagent, which THREE parameters or sub-statements can be configured under the 'set system services jpagent' hierarchy? (Choose three)

Accepted Answer

traceoptions. Under the 'set system services jpagent' hierarchy, the jpagent (Junos REST API agent) supports the 'traceoptions' sub-statement (B), which enables logging and debugging of jpagent activity via configured trace files and flags. It also supports the 'https' sub-statement (C), which enables the HTTPS transport for the REST API and allows configuration of TLS-related parameters such as certificates and addresses. The 'port' parameter (E) is configurable to specify the TCP port on which jpagent listens for REST API requests (default 3000). Options A (bgp-peer-group) and D (ethernet-switching) are not valid under 'system services jpagent'; bgp-peer-group belongs to BGP configuration and ethernet-switching is a switching-options/protocols hierarchy, neither of which is a jpagent parameter.

Answer

bgp-peer-group

Answer

ethernet-switching

Question 19

An automation engineer needs to enable and configure the Junos REST API service on an SRX Series device using the CLI. Which configuration hierarchy must be used to enable the service and configure its transport protocol?

Accepted Answer

set system services web-management https. The Junos REST API service is configured under the 'system services web-management http' or 'https' hierarchy in the Junos CLI.

Answer

set management-plane api rest

Answer

set system services rest http port 3000

Answer

set protocols rest-api enable

Question 20

An administrator wants to fetch operational data representing interface statistics using the Junos REST API by issuing an HTTP GET request. Which URI structure correctly targets the 'get-interface-information' RPC via the REST API endpoint?

Accepted Answer

/api/st/rest/rpc/get-interface-information. The Junos REST API allows executing operational RPCs using the path '/rpc/get-interface-information'.

Answer

/api/core/rest/rpc/get-interface-information

Answer

/api/space/rest/rpc/get-interface-information

Answer

/api/font/rest/rpc/get-interface-information