JNCIA-DevOps Practice Test 18 — 15 Questions

Question 1

When establishing a NETCONF session over SSH, which standard capability announcement is exchanged during the initial hello message phase?

Accepted Answer

urn:ietf:params:netconf:base:1.0. NETCONF capabilities are exchanged in <hello> messages at session startup, referencing URIs like urn:ietf:params:netconf:base:1.0.

Answer

http://xml.juniper.net/junos/rpc/v1

Answer

netconf:params:xml:ns:netconf:base:2.0

Answer

urn:juniper:params:netconf:ssh:1.0

Question 2

Which python module is part of the standard library that can be used to parse XML responses returned by NETCONF?

Accepted Answer

xml.etree.ElementTree. Python's built-in xml.etree.ElementTree module provides tools for parsing and navigating XML data.

Answer

netconf.parser

Answer

xml2dict

Answer

json

Question 3

Which TWO data serialization formats can an automation engineer request using the 'Accept' header in a Junos REST API GET request? (Choose two)

Accepted Answer

application/json. The Junos REST API supports application/json and application/xml in Accept headers to return responses in the desired format.

Answer

application/yaml

Answer

text/csv

Answer

application/octet-stream

Question 4

You need to load a set of configuration changes into the Junos candidate datastore from an inline XML string using NETCONF. Which RPC element is used to load configuration data?

Accepted Answer

. The RPC is a Juniper-specific extension used within NETCONF to load configuration data with formats like XML, text, or set.

Answer

<update-candidate>

Answer

<set-config>

Answer

<edit-config>

Question 5

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 6

Which statement best describes the primary architectural difference between NETCONF and the Junos REST API?

Accepted Answer

NETCONF is a connection-oriented RPC protocol over SSH, while Junos REST API is a resource-oriented web API over HTTP/HTTPS.. NETCONF is a session-oriented, connection-oriented protocol running over SSH (port 830) using XML-encoded RPCs. The Junos REST API is a stateless (at the HTTP layer) resource-oriented web API running over HTTP/HTTPS (port 3000/3443) supporting JSON and XML.

Answer

NETCONF only supports JSON, while REST API only supports XML.

Answer

There are no architectural differences; REST API is simply an XML parser for NETCONF.

Answer

NETCONF is a web-based stateless API, whereas REST API requires a persistent SSH session.

Question 7

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 8

You want to retrieve the software version and hardware inventory of a Junos device in a single NETCONF request. Which RPC tag combines both hardware and software details?

Accepted Answer

Executing multiple RPCs or using container elements such as and .. The and RPCs can be combined, or can be used; however, Junos provides specific RPCs like .

Answer

<get-inventory-all>

Answer

<retrieve-device-state>

Answer

<get-hardware-and-software>

Question 9

When executing a NETCONF transaction on a Junos device, an automation script encounters an error or needs to discard changes made in the candidate datastore. Which THREE RPC elements or concepts apply to discarding or rolling back changes in Junos NETCONF workflows? (Choose three.)

Accepted Answer

Unlocking the configuration datastore using ensures other administrators are not permanently locked out if a script terminates unexpectedly.. Junos NETCONF supports discarding candidate changes via , rolling back committed configurations via rollback IDs in commit operations, and unlocking datastores upon error cleanup.

Answer

The <rollback-config> operation is a standalone top-level NETCONF protocol operation defined in RFC 6241.

Answer

The <abort> RPC can be used mid-transaction to cancel an active streaming configuration edit.

Question 10

You are writing a script that uses PyEZ to load a Junos configuration file, but you want to replace an entire hierarchy level (e.g., protocols bgp) rather than merging the changes. Which parameter should you pass to the load method?

Accepted Answer

action='replace'. The action='replace' parameter tells PyEZ to replace the specified hierarchy level in the candidate configuration.

Answer

overwrite=True

Answer

merge=False

Answer

mode='override'

Question 11

An administrator issues a NETCONF <get-config> request targeting the candidate datastore and includes a namespace prefix that does not match the device's loaded YANG/XML schema namespace. How does Junos respond?

Accepted Answer

The device returns an <rpc-error> indicating an invalid namespace or unrecognized element.. Mismatched or unknown namespaces in NETCONF requests result in a malformed message or invalid-element rpc-error.

Answer

The device falls back to default CLI parsing mode.

Answer

The session is immediately terminated by the SSH server.

Answer

The device automatically strips the namespace prefix and processes the request.

Question 12

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 13

An engineer applies a configuration change using NETCONF with <edit-config> and specifies default-operation="replace" at the top level, but includes an element with operation="merge". How does Junos evaluate this?

Accepted Answer

The specific element operation ('merge') takes precedence over the transaction-level default-operation ('replace').. Per-element operation attributes override the default-operation specified at the transaction level.

Answer

The transaction fails because default-operation and element operations conflict.

Answer

The device rolls back the configuration due to ambiguous parameters.

Answer

The default-operation takes precedence, ignoring the merge attribute.

Question 14

Which TWO HTTP response status codes indicate a successful Junos REST API request where data was successfully retrieved or modified? (Choose two)

Accepted Answer

200 OK. 200 OK and 204 No Content (or 201 Created) indicate successful API execution depending on the method.

Answer

404 Not Found

Answer

401 Unauthorized

Answer

500 Internal Server Error

Question 15

You are configuring NETCONF traceoptions on a Junos device to debug an XML parsing issue. Which configuration statement enables logging of all NETCONF protocol messages to a file named 'netconf-debug.log'?

Accepted Answer

set system services netconf traceoptions file netconf-debug.log
set system services netconf traceoptions flag all. Traceoptions under the netconf system services hierarchy control logging of NETCONF traffic.

Answer

set protocols netconf traceoptions file netconf-debug.log flag detail

Answer

set security netconf logging file netconf-debug.log

Answer

set system netconf trace file netconf-debug.log level debug