Apparatus, methods, and related data structures for validating a routing configuration in a communication system are disclosed. Routing information in a communication system is passively collected, illustratively from routing protocol advertisement messages. A routing configuration of the communication system is validated based on the collected routing information. Validation may involve comparing information associated with electronic addresses in an address space of the communication system with the collected routing information, and also or instead comparing an intended routing configuration with an explicit routing configuration, for example. A data structure may include information indicating an electronic address and information indicating a result of validating a routing configuration associated with the electronic address.