JNCIA-DevOps NETCONF And XML API Practice Test 3 — 15 Questions

Question 1

An automation engineer is using the Junos XML API over SSH to retrieve operational data. The engineer wants to compare the behavior of two different Junos XML API request types: one that returns a fixed, predefined set of data and one that allows on-demand execution of CLI commands. Which two statements correctly describe the Junos XML API request types that support these behaviors? (Choose two.)

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

Accepted Answer

The RPC allows execution of an arbitrary CLI command and returns the output in XML format.. The Junos XML API provides both predefined RPCs, such as , which return fixed XML structures for common operational commands, and the RPC, which executes arbitrary CLI commands and returns XML output. These two mechanisms cover the fixed and on-demand behaviors. Other RPCs like or serve configuration purposes and do not retrieve operational data.

Answer

The <load-configuration> RPC retrieves operational data when used with the 'action' attribute set to 'get'.

Answer

The <get-software-information> RPC returns a fixed set of software version details and does not accept a command string.

Answer

The <get-config> RPC returns operational data such as interface statistics when a subtree filter is applied.

Question 2

A network automation engineer is using the Junos XML API to retrieve interface statistics from a Junos device. The engineer sends a RPC with the tag. The response includes a large amount of data, and the engineer wants to reduce the payload by retrieving only the statistics for a specific interface, ge-0/0/0. Which RPC modification should the engineer make?

Accepted Answer

Use a subtree filter with the ge-0/0/0 element within the RPC.. To retrieve statistics for a specific interface, the engineer should use the element as a filter within the RPC. This is the documented method for restricting output to a particular interface. Other approaches like attribute filters or generic elements are not supported for this operational RPC.

Answer

Include a <filter> element with type="subtree" and an XPath expression selecting the interface.

Answer

Add a ge-0/0/0 element inside the RPC.

Answer

Add an attribute filter="interface-name='ge-0/0/0'" to the <get-interface-information> RPC.

Question 3

A network automation engineer is using the Junos XML API over SSH to configure a device. The engineer sends an <edit-config> RPC with the 'test-option' attribute set to 'test-then-set'. What is the effect of this attribute?

Accepted Answer

The device validates the configuration and applies it to the candidate datastore only if validation succeeds.. The 'test-option' attribute in NETCONF <edit-config> controls validation behavior. Setting it to 'test-then-set' causes the device to validate the configuration before applying it to the candidate datastore. If validation succeeds, the configuration is loaded; if it fails, an error is returned and the candidate remains unchanged. This is a safety mechanism to avoid staging invalid configurations.

Answer

The device bypasses the candidate datastore and loads the configuration directly into the running configuration.

Answer

The device validates the configuration syntax and semantics, and if successful, commits the changes immediately.

Answer

The device applies the configuration to the candidate datastore without any validation, then validates before commit.

Question 4

An automation engineer is writing a Python script that uses the Junos XML API over NETCONF to retrieve the running configuration of a specific interface (ge-0/0/0) on a Junos device. The script must return only the configuration hierarchy for that interface, excluding all other interface and protocol configuration. Which NETCONF operation and filter type should the engineer use?

Accepted Answer

with a filter containing a subtree filter with a element matching ge-0/0/0.. The operation is the standard NETCONF operation for retrieving configuration data from a specified datastore, such as the running configuration. Subtree filtering allows precise selection of the interface hierarchy by matching the interface name. Using would retrieve operational data instead, XPath is not supported by Junos, and adding a description filter would exclude other configuration elements.

Answer

with a filter containing a subtree filter with a element containing ge-0/0/0 and filter.

Answer

<get-config> with an XPath filter using the expression //interface[name='ge-0/0/0'] to select the interface configuration.

Answer

with a filter containing a subtree filter with a element matching ge-0/0/0.

Question 5

A network automation engineer needs to discover the YANG capabilities advertised by a Junos device before generating configuration templates. The engineer opens an SSH session to the device and starts the NETCONF subsystem. Which NETCONF operation should the engineer send to retrieve the list of supported YANG modules and capabilities?

Accepted Answer

. The operation is specifically designed to return the set of capabilities supported by a NETCONF server, including YANG modules. The engineer needs this information to know which modules and features are available before creating templates. Other operations such as or serve different purposes and do not provide the full capability list.

Answer

<hello>

Answer

<get-schema>

Answer

<get-configuration>

Question 6

An automation engineer is using the Junos XML API over NETCONF to retrieve configuration data. The engineer wants to filter the response to include only specific configuration elements. Which two filtering methods are supported by Junos for <get-config> operations? (Choose two.)

Accepted Answer

Subtree filtering using XML elements that match the configuration hierarchy.. Junos supports two filtering methods for <get-config>: subtree filtering and attribute match filtering. Subtree filtering uses XML elements to select configuration nodes, while attribute match filtering uses the match attribute on elements to filter by leaf values. XPath, regular expressions, and XSLT are not supported for NETCONF filtering on Junos devices.

Answer

Regular expression filtering using pattern matching on configuration values.

Answer

XPath filtering using expressions to select nodes.

Answer

XSLT filtering using stylesheets to transform the response.

Question 7

A network automation engineer is using the Junos XML API to retrieve operational data from a device. The engineer needs to filter the output to include only specific interface details, such as the interface name and operational status, to reduce the payload size. Which two XML filtering techniques can the engineer use with the Junos XML API to achieve this? (Choose two.)

Accepted Answer

Use the element with a 'type' attribute set to 'subtree' and specify the desired XML subtree.. NETCONF defines two filter types: subtree and xpath. Both can be used with the operation to retrieve operational data. Subtree filtering matches a specified XML structure, while XPath filtering uses XPath expressions to select nodes. These methods allow precise selection of interface name and status, reducing payload size. Other options are either not standard or retrieve configuration instead of operational data.

Answer

Use the <filter> element with a 'type' attribute set to 'regex' and provide a regular expression.

Answer

Use the <get-interface-information> RPC with a 'terse' parameter to automatically limit output to name and status.

Answer

Use the <get-config> operation with a 'filter' element to retrieve operational data.

Question 8

Which NETCONF RPC tag is used to gracefully terminate an active NETCONF session with a Junos device?

Accepted Answer

. The RPC requests graceful termination of the NETCONF session.

Answer

<terminate-session>

Answer

Answer

<kill-session>

Question 9

While executing a NETCONF edit-config operation, you want to ensure that any syntax errors or invalid statements immediately cause the device to roll back the entire transaction without applying partial changes. Which parameter achieves this?

Accepted Answer

rollback-on-error. The error-option element with the value 'rollback-on-error' instructs the device to abort and roll back if any error occurs.

Answer

test-then-set

Answer

<default-operation>none</default-operation>

Answer

stop-on-error

Question 10

Which XML tag encapsulates the entire response returned by a Junos device in reply to a valid NETCONF RPC request?

Accepted Answer

. Every NETCONF response from a Junos device is wrapped in an tag.

Answer

<response-data>

Answer

<xml-reply>

Answer

<netconf-response>

Question 11

You need to lock the candidate configuration datastore in your NETCONF script to prevent concurrent modifications by other administrators. Which XML element accomplishes this?

Accepted Answer

. The RPC takes a target element specifying which datastore to lock, such as the candidate datastore.

Answer

<lock-config>

Answer

<acquire-lock>

Answer

<exclusive-edit>

Question 12

You are writing a Python script to retrieve the operational state of interfaces from a Junos device using NETCONF. Which XML RPC element must be enclosed within the <rpc> tag to request operational data?

Accepted Answer

. The rpc tag is used to retrieve both configuration and operational data, whereas is restricted to configuration data.

Answer

<pull-operational>

Answer

<get-rpc-reply>

Answer

<get-config>

Question 13

An administrator issues an edit-config RPC with default-operation="replace" targeting the candidate datastore. What is the impact on the existing configuration on the Junos device?

Accepted Answer

The entire target configuration datastore is replaced by the configuration provided in the RPC payload.. The replace operation overwrites the entire target configuration datastore with the configuration provided in the RPC message.

Answer

The configuration is merged, and any conflicting nodes generate a validation error.

Answer

The candidate datastore is cleared, and only the default factory configuration is loaded.

Answer

Only the specific leaf nodes provided in the RPC are updated; everything else remains intact.

Question 14

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 15

An engineer executes a NETCONF <discard-changes> RPC. What is the precise effect of this operation on the Junos device?

Accepted Answer

It discards all uncommitted changes currently sitting in the candidate datastore, reverting it to match the running datastore.. The <discard-changes> RPC discards any uncommitted changes present in the candidate configuration datastore.

Answer

It clears all active alarms and operational logs from the routing engine.

Answer

It terminates all active NETCONF sessions currently connected to the device.

Answer

It reverts the active running configuration to the factory default state.