JN0-423 Sample Questions & Answers

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.

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.

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.

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.

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.

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.

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.

gRPC leverages TLS for transport security. For robust security, mutual TLS (mTLS) is often used, where both the client (collector) and the server (Junos device) present certificates to authenticate each other, ensuring both parties are trusted.

TLS and mTLS rely on X.509 certificates to establish identity and enable encryption. Both the Junos device and the collector must be configured with a certificate and private key, and they must trust the Certificate Authority (CA) that signed each other's certificates.

The correlate action within an event policy is used for event damping. The time-period option specifies, in seconds, the window during which subsequent identical events will be suppressed after the first one triggers the action. A value of 300 seconds (5 minutes) will ensure that after one UI_COMMIT_COMPLETED event triggers the script, all other UI_COMMIT_COMPLETED events are ignored for the next 5 minutes.

True. A leaf-list is a YANG node type that defines a sequence of leaf nodes, each containing a value of a particular simple type (e.g., string, integer). By default, the values in a leaf-list must be unique, and their order is significant.