JNCIA-DevOps Practice Test 19 — 15 Questions

Question 1

Which TWO methods can an administrator use to verify that a Python script successfully established a NETCONF session with a Junos device? (Choose two)

Accepted Answer

Run 'show system netconf sessions' on the Junos CLI.. Session verification can be performed by checking active system sessions on the device or inspecting script connection outputs.

Answer

Review BGP neighbor adjacency tables.

Answer

Verify physical interface link LEDs.

Answer

Check the device temperature sensors.

Question 2

You are writing a Python script to retrieve interface statistics from a Junos device using the REST API. You use HTTP Basic Authentication. Which HTTP header must be included to pass the encoded credentials correctly?

Accepted Answer

Authorization. HTTP Basic Authentication requires the 'Authorization' header containing the keyword 'Basic' followed by the Base64-encoded username:password string.

Answer

Proxy-Authenticate

Answer

Junos-Auth-Token

Answer

X-API-Key

Question 3

An engineer needs to establish a NETCONF session with a Junos device securely. Which underlying transport protocol does NETCONF use by default according to RFC 6242?

Accepted Answer

TCP port 830. NETCONF over SSH is defined in RFC 6242 and uses TCP port 830 by default for secure transport.

Answer

TCP port 22

Answer

TCP port 443

Answer

UDP port 830

Question 4

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 5

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.. Administrators can check jpagent traceoptions logs, messages log (/var/log/messages), and HTTP response headers/status codes for debugging.

Answer

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

Answer

BGP peer state packet captures in Wireshark.

Question 6

Which TWO configuration datastores are commonly supported and utilized when interacting with Junos devices via NETCONF? (Choose two)

Accepted Answer

candidate. Junos primarily supports the candidate and running datastores for configuration management via NETCONF.

Answer

startup

Answer

ephemeral

Answer

factory

Question 7

When retrieving operational data using the Junos XML API, how do you request pretty-printed or indented XML output?

Accepted Answer

Include the indent="true" attribute in the RPC request element.. Junos XML API supports formatting attributes such as indent="true" in RPC requests.

Answer

Add true inside the tag.

Answer

Use the NETCONF command-line flag --format-xml.

Answer

Set the environment variable JUNOS_XML_INDENT=1 in your shell.

Question 8

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.. Junos REST API utilizes standard HTTP/HTTPS transport and commonly returns JSON formatted responses, whereas NETCONF uses port 830 and XML payloads.

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 9

You want to retrieve only the system hostname from the Junos running configuration using NETCONF. Which filtering technique is most efficient?

Accepted Answer

Subtree filtering using XML element tags matching the configuration hierarchy. Tag-based filtering allows requesting specific configuration hierarchies by including empty container tags in the <get-config> request.

Answer

XPath expression filtering via the select attribute

Answer

Regular expression pattern matching within the <filter> attribute

Answer

Retrieving the entire configuration and parsing it locally with a Python script

Question 10

You are troubleshooting a NETCONF session where the client sent an improperly formatted XML payload. Where would you expect to find detailed error logging related to this malformed XML request on the Junos device?

Accepted Answer

NETCONF traceoptions output file or /var/log/messages. Junos logs NETCONF and XML API activity, including parsing errors, into the traceoptions log file if configured, or general system logs.

Answer

/var/log/netconf.log

Answer

/var/db/config/juniper.conf.gz

Answer

/etc/netconf/errors.xml

Question 11

When executing a NETCONF request, you specify but omit any filtering tags. What is returned in the ?

Accepted Answer

The complete configuration contained within the candidate datastore.. Omiting filter tags on a <get-config> request returns the entire contents of the specified configuration datastore.

Answer

An rpc-error stating that a filter is mandatory.

Answer

Only the differences between candidate and running configurations.

Answer

Only the top-level system hierarchy statements.

Question 12

An engineer executes an HTTP GET request to retrieve interface operational details using the Junos REST API, but receives a 403 Forbidden status code. What is the most likely reason?

Accepted Answer

The authenticated user account lacks sufficient RBAC permissions to access the requested resource.. A 403 Forbidden status code indicates that the authentication credentials provided were valid (otherwise it would be 401), but the user account lacks the necessary RBAC permissions or class privileges to access the requested resource.

Answer

The HTTP request method should have been POST.

Answer

The Accept header was missing from the GET request.

Answer

The jpagent service is disabled on the device.

Question 13

When comparing error handling between NETCONF and the Junos REST API, how are protocol-level errors communicated back to the client?

Accepted Answer

NETCONF embeds error details inside XML tags, whereas REST API uses standard HTTP status codes accompanied by structured error response bodies.. NETCONF communicates errors via XML elements embedded in the response envelope. The Junos REST API leverages standard HTTP status codes (such as 400 Bad Request, 401, 403, 404, 500) combined with detailed error payloads in the response body.

Answer

NETCONF uses HTTP status codes, while REST API uses XML <rpc-error> tags.

Answer

NETCONF and REST API both use identical JSON error envelopes defined by RFC 7807.

Answer

Both protocols rely exclusively on system syslog files to report errors to the client API.

Question 14

During troubleshooting of a Python script using the ncclient library to interact with a Junos device, an automation engineer observes a 'rpc-error' response containing an error-tag of 'operation-failed'. Upon examining the Junos system logs, it is discovered that the candidate configuration had syntax errors introduced by an uncommitted previous session. Which NETCONF capability negotiation mechanism ensures that the client is aware of the exact XML schema constraints before sending the RPC?

Accepted Answer

NETCONF capability URIs exchanged during the initial hello message exchange.. NETCONF hello messages exchange capabilities, which include URLs pointing to XML namespaces and data models such as YANG modules or Junos specific DTDs/XSDs.

Answer

The <get-schema> RPC operation defined in RFC 6020.

Answer

The automatic download of Junos PyEZ schema definitions during the SSH handshake phase.

Answer

The automated execution of a pre-flight XML validation check via the <validate> RPC.

Question 15

An automation script connects to a Junos device using NETCONF over SSH and retrieves the running configuration. The engineer notices that the retrieved XML elements contain attributes like 'operation="inherit"'. What do these attributes represent in the context of Junos XML API?

Accepted Answer

They describe the configuration hierarchy manipulation state, indicating whether a statement is inherited from apply-groups or explicitly defined.. Junos XML output uses attributes such as 'operation' to indicate how configuration statements relate to inheritance, deletion, or modification within hierarchical structures.

Answer

They indicate the automation user permission level required to modify that specific node.

Answer

They represent transient states of the NETCONF parser buffer indicating stream synchronization status.

Answer

They represent mapping hints for how Junos hierarchical statements map to hierarchical template inheritances during operational state generation.