Automation and DevOps, Specialist (JNCIS-DevOps) Free Sample Questions

Event scripts execute in an environment that does not have an open configuration session by default. To make a configuration change, the script must explicitly open a database connection (e.g., using Junos_Context['user-context']['jcs:open']), load the configuration change, and then commit it. Simply invoking a set command does not alter the persistent configuration.

The correct way to subscribe to specific data points is to list each full sensor path in the gNMI Subscribe RPC. Instead of using a wildcard path like /interfaces/interface[name='ge-0/0/0']/state/counters/, the client should request /interfaces/interface[name='ge-0/0/0']/state/counters/in-octets and /interfaces/interface[name='ge-0/0/0']/state/counters/out-octets explicitly. This ensures the device only streams the requested data, which is the most efficient method.

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.

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.

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.

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.