In Juniper Apstra, resources such as Autonomous System (AS) numbers, IP addresses, and VLAN IDs are managed within pools. These resource pools can be defined with two distinct scopes. They can be created at a global level, making them available for assignment across all blueprints managed by the Apstra controller. Alternatively, a resource pool can be created within a specific blueprint, limiting its scope and usage to only that blueprint. This provides flexibility for both shared resource management and blueprint-specific allocations.

A. User-defined resources are supported.

While this statement is true, it is less precise than option C, which correctly describes the fundamental scoping mechanism for all resource pools, whether default or user-defined.

B. The scope of a pool is limited to a single blueprint.

This is incorrect. Resource pools can also be defined at the global level, making them available to all blueprints.

D. Only the default resources are supported globally.

This is incorrect. Users can create their own custom resource pools at the global level, not just use the default ones.

1. Juniper Apstra User Guide, "Resource Pools". This section explicitly states, "You can create resource pools at the global level (Design > Global) or at the blueprint level (Staged > Blueprint > Resources)."

2. Juniper TechLibrary, "Apstra Resource Management". The documentation details the hierarchy and scope of resource pools, confirming that pools can be either global or blueprint-specific.