Free JN0-423 sample questions

Correct answer: `grouping` defines a reusable block of nodes, and `uses` instantiates that block within the data model.

In YANG, `grouping` is used to define a collection of nodes (containers, lists, leaves) that can be reused in multiple places. It acts like a template or a macro. The `uses` statement then references a `grouping` to place that defined block of nodes into the current position in the schema tree. This promotes modularity and avoids repetition in the data model.

Correct answers: A `provider` block for `junos`; A `resource` block such as `junos_config_set`

The `provider` block is essential as it tells Terraform how to interact with the target API. For Junos devices, the `juniper/junos` provider must be declared and configured with connection details like the host and credentials.

A `resource` block defines a piece of infrastructure. To apply configuration, a resource like `junos_config_set` or `junos_config_object` is used to specify the desired Junos configuration in `set` command format or another structured format.

Correct answer: The candidate configuration

Commit scripts operate on the candidate configuration after it has been merged with the running configuration but before it is validated by the system. The script should parse this post-inheritance candidate configuration to check for the logical inconsistency between the interface's VLAN membership and the defined VLANs.

Correct answer: True

True. Junos OS implements gNMI `Set` RPCs as atomic operations. The device treats the entire set of updates, replaces, and deletes within a single `Set` request as a single transaction. It performs a syntax check, and if successful, commits the changes. If any part of the transaction fails, the device rejects the entire change and rolls back to the previous state, ensuring configuration consistency.

Correct answer: OpenConfig YANG models

OpenConfig is an industry initiative to define vendor-neutral YANG data models for network configuration and telemetry. By using the OpenConfig BGP models, the company can create a single, standardized representation of their BGP configuration that can be applied to both Juniper and Arista devices (assuming they both support the required OpenConfig models), fulfilling the core requirement.

Correct answer: `set cli op-script-alias show-high-cpu script get-high-cpu.slax`

The correct hierarchy to create a CLI alias for an op script is `[edit cli]`. Within this stanza, the `op-script-alias` statement is used. The command would be `set cli op-script-alias show-high-cpu script get-high-cpu.slax`. This maps the user-friendly operational command `show high-cpu` to the specified op script file.

Correct answer: JSD-based, because it allows for the development of custom, stateful daemons that run persistently on the device.

JSD (Junos Service Daemon)-based automation, using the Juniper Extension Toolkit (JECT), is designed for creating custom, on-box applications (daemons) that run independently and persistently. This architecture is ideal for stateful applications that need to maintain logic over time and listen for external events, which aligns perfectly with the project requirements. MGD-based automation (like commit scripts) is typically stateless and event-triggered.

Correct answer: It defines the service methods and message structures, and is used to generate client-side code stubs.

The `.proto` file is the Interface Definition Language (IDL) for gRPC. It defines the API contract, including the available RPC methods (services) and the format of the data messages being exchanged. The `protoc` compiler uses this file to generate language-specific client and server code (stubs), which simplifies the development process by providing pre-built functions and classes for interacting with the gRPC service.

Correct answer: leaf timeout { type uint32 { range "60 .. 3600"; } }

The `range` statement is a substatement to the `type` definition in YANG. It is used to restrict the value space for integer and decimal types. The correct syntax uses two dots (`..`) to separate the minimum and maximum values of the inclusive range.

Correct answer: JSNAPy

JSNAPy (Junos Snapshot Administrator in Python) is the tool purpose-built for capturing operational state snapshots of a Junos device before and after a change. It uses YAML or JSON test files to define what data to collect and the conditions to test (e.g., route count is_equal, interface is_up). It can then generate a diff report highlighting any deviations from the expected state.