Multiple incoming requests from unknown clients

Looked at the docs and am still unclear here. What is the best practice for handling incoming requests which require different policies (i.e. secret keys) whereby the client IP is unknown? Was thinking there may be a to setup virtual servers which listen on different server IPs somehow? Few thoughts: - route based on client configured DNS: SOMEPREFIX.mydomain.com - accept all and pass other RADIUS attributes down (not preferred) Thanks, Diego