JNCIA-DevOps Practice Test 10 — 10 Questions

Question 1

Which Python module is part of the standard library and provides functions to serialize and deserialize JSON data?

Accepted Answer

json. The 'json' module is part of the Python standard library and requires no external installation.

Answer

requests

Answer

yaml

Answer

junos-eznc

Question 2

Which THREE mechanisms are valid methods for authenticating and establishing a NETCONF session with a Junos device? (Choose three)

Accepted Answer

Remote RADIUS or TACACS+ AAA server integration via SSH transport. Option B is correct because NETCONF sessions are established over SSH (default TCP port 830), and the client can authenticate with a username and password just like a standard SSH login. Option C is correct because SSH public key authentication is a supported method for authenticating the NETCONF-over-SSH session, using the client's private key matched against an authorized key on the Junos device. Option A is correct because Junos can delegate authentication of NETCONF-over-SSH users to external RADIUS or TACACS+ AAA servers, so credentials are validated by the remote AAA server rather than only local accounts. Option D is wrong because NETCONF requires authenticated credentials and does not permit anonymous guest access. Option E is wrong because NETCONF uses SSH transport, not unencrypted cleartext Telnet on TCP port 23.

Answer

Anonymous guest access without credentials

Answer

Unencrypted cleartext Telnet on TCP port 23

Question 3

Which THREE features are provided by the Junos REST API daemon (jpagent) when running on a Junos device? (Choose three)

Accepted Answer

Translation between REST requests/JSON/XML payloads and Junos configuration/operational structures.. Option B is correct because jpagent's core function is to translate incoming REST requests and their JSON or XML payloads into Junos configuration and operational data structures, allowing the REST API to manipulate the same candidate/active configuration and operational command infrastructure used by the CLI. Option C is correct because jpagent manages the HTTP and HTTPS listeners, including binding to configurable ports (for example via the 'set system services rest http port' or 'https port' configuration), so clients can reach the REST endpoint. Option D is correct because jpagent performs authentication validation for REST requests against local user accounts or external AAA (RADIUS/TACACS+) before allowing access to Junos resources. Option A is incorrect because kernel-level packet forwarding and ASIC line-card optimization are handled by the Packet Forwarding Engine and related hardware/software components, not by the REST API daemon. Option E is incorrect because BGP route reflection is a routing protocol function configured under BGP, not a service provided by jpagent.

Answer

Kernel-level packet forwarding optimization for ASIC line cards.

Answer

Autonomous BGP route reflection across core routing instances.

Question 4

What is the purpose of the <hello> element exchanged immediately after establishing a NETCONF SSH session?

Accepted Answer

To exchange supported protocol capabilities and namespace identifiers.. The <hello> element is used by both client and server to exchange supported capabilities and session parameters.

Answer

To authenticate the SSH username and password.

Answer

To request an immediate reboot of the Junos routing engine.

Answer

To lock the candidate configuration database automatically.

Question 5

An automation script makes a REST API request to modify a Junos configuration. To ensure that the changes are validated and committed in a single workflow step without leaving dangling candidate changes, how can the commit parameter be handled?

Accepted Answer

Include the 'action=commit' query parameter or commit body flag with the configuration request.. The Junos REST API allows query parameters or header flags (such as '?action=commit' or dedicated commit instructions) to automatically commit changes made during a configuration modification request.

Answer

Issue an HTTP GET request to /api/configuration/commit.

Answer

Set the Transfer-Encoding header to 'commit'.

Answer

Send a separate SSH command because REST cannot commit configurations.

Question 6

Which THREE error-tag values defined in NETCONF RFC 6241 may be returned by a Junos device when an edit-config operation fails validation? (Choose three)

Accepted Answer

invalid-value. Option B, invalid-value, is correct because RFC 6241 defines this error-tag for when a configuration value is syntactically or semantically invalid, which is exactly what a Junos device reports when edit-config content fails validation checks such as range or type constraints. Option C, data-exists, is correct because it is the standard NETCONF error-tag returned when a create operation targets data that already exists, a common validation failure during edit-config processing. Option E, missing-element, is correct because RFC 6241 specifies this tag for when a required element is absent from the configuration being edited, another typical validation error. Option A, syntax-timeout, is not a defined NETCONF error-tag in RFC 6241, and option D, buffer-overflow, is likewise not part of the RFC 6241 error-tag enumeration, so neither belongs.

Answer

syntax-timeout

Answer

buffer-overflow

Question 7

Which THREE error-type values are defined in the NETCONF protocol specification (RFC 6241) for categorizing <rpc-error> messages? (Choose three)

Accepted Answer

rpc. RFC 6241 defines the element of an with exactly three enumerated values: rpc (A), transport (C), and protocol (D). The rpc value indicates an error occurred during RPC processing on the server, such as an invalid or malformed RPC element. The transport value indicates an error at the transport-protocol layer, such as a dropped connection or authentication failure. The protocol value indicates a violation of the NETCONF protocol semantics, such as an unknown operation or missing mandatory parameter. The unmarked options hardware (B) and kernel (E) are not part of the RFC 6241 enumeration; they resemble syslog or SNMP-style categories and have no defined role in NETCONF error reporting.

Answer

hardware

Answer

kernel

Question 8

Which THREE distinct operational states or configuration views can be queried using specific Junos XML API RPCs? (Choose three)

Accepted Answer

System information via . Option A is correct because the Junos XML API provides the RPC, which returns operational system data such as hostname, uptime, and platform details from the device. Option C is correct because is a valid Junos RPC that queries the hardware inventory of the chassis, including components like FPCs, PICs, and power supplies. Option E is correct because is a standard Junos RPC used to retrieve operational state and statistics for interfaces, equivalent to the CLI 'show interfaces' command. Option B is not correct because there is no Junos XML API RPC named ; BGP routing information is retrieved through other RPCs such as or . Option D is not correct because is not a valid Junos RPC for retrieving firewall filter logs; packet capture and log retrieval use different mechanisms and commands.

Answer

BGP routing table via <get-bgp-kernel-table>

Answer

Firewall filter logs via <get-security-packet-capture>

Question 9

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 10

You are writing a Python script that parses a multi-document YAML stream containing Junos device site configurations. One of the documents contains a custom YAML tag. When parsing with yaml.safe_load_all(), how does the safe loader handle custom tags?

Accepted Answer

It raises a ConstructorError unless a custom constructor is registered.. The safe loader in PyYAML does not know how to construct objects from custom tags by default and will raise a ConstructorError unless a custom constructor has been explicitly registered.

Answer

It converts the tagged object into a JSON equivalent.

Answer

It automatically evaluates the custom tag using Python eval().

Answer

It ignores the tag and loads the scalar value as a plain string.