What must be configured for Cisco ACI APIC fabric to enable Panorama to retrieve endpoint IP-address-to-tag-mapping information?

The correct answer is the monitoring definition. In a Cisco ACI environment, monitoring definitions are essential for data collection and provide the necessary configuration to facilitate the retrieval of specific telemetry data, which includes endpoint IP-address-to-tag-mapping information. This configuration allows Panorama to effectively monitor and retrieve endpoint information from the Cisco ACI fabric.

By defining the appropriate monitoring settings within the ACI configuration, you can ensure that Panorama has access to the data it needs to map IP addresses to endpoint tags. This is critical for visibility in network security policies, allowing for better management of network resources and improved overall operational efficiency within the data center environment.

In contrast, the other options, while relevant to the Cisco ACI architecture, do not specifically address the requirement for Panorama to access endpoint IP-to-tag information. Service graphs pertain to the deployment of service chains, bridge domains relate to Layer 2 segmentation, and VMM focuses on integrating virtualized environments. Thus, they do not serve the function of enabling endpoint data retrieval as monitoring definitions do.