Which of the following is a challenge when using an NVA for spoke-to-spoke communication in Azure?

User-Defined Route Management at scale is a significant challenge when using a Network Virtual Appliance (NVA) for spoke-to-spoke communication in Azure. In a multicloud or hybrid cloud environment, managing routes can become complex, particularly when dealing with multiple spokes and their respective communication paths. Each spoke may require specific routing to ensure traffic is directed correctly through the NVA, leading to an increase in overhead as the number of spokes grows.

As more user-defined routes are implemented to manage this traffic, maintaining these routes can become cumbersome. This complexity can lead to potential misconfigurations or oversight in routing, affecting the performance and reliability of network communication between spokes.

Although the other options present relevant considerations in the context of NVAs and spoke-to-spoke communication, the challenge of route management specifically illustrates a direct operational overhead that must be navigated in Azure environments, making it a critical focus for those implementing this type of architecture.