EIGRP Stub Receive-Only Mode Configuration

The scenario requires preventing a data center router from advertising any WAN routes to its neighbors. In EIGRP, the stub feature is designed to limit the amount of routing information exchanged with specific neighbors, typically in hub-and-spoke topologies.

Option C, Configure the stub router in receive-only mode, is the correct action. When an EIGRP router is configured as a stub with the receive-only parameter, it advertises only that it is a stub to its neighbors and does not send any routing updates itself. It can still learn routes from neighbors (hence 'receive'), but it will not advertise any of its own routes, effectively satisfying the requirement to ensure no WAN routes are advertised from this device.

Option A is incorrect because redistributed mode allows the router to advertise static and connected routes, which violates the 'no advertisement' constraint. Option B is incorrect because advertising a default route still constitutes advertising a route, and more importantly, standard stub behavior usually involves advertising connected and summary routes unless specifically restricted; however, receive-only is the explicit configuration for zero advertisements. Option D is incorrect because summarization reduces the number of routes but does not stop advertisements entirely, and it applies to local subnets rather than controlling the router's overall advertisement behavior toward the WAN.

This knowledge covers the trade-offs between stub modes (connected, static, summary) versus receive-only. If the requirement were to allow static route advertisements, the answer would shift to static mode. Getting this wrong could lead to unnecessary routing table bloat or instability in the data center by flooding it with WAN-specific routes.