A preferred embodiment of the present invention includes a method and apparatus for routing an IP packets in a network of client systems. The router forwards IP packets between the client systems and the server systems. More specifically, the router can be pre-configured to include one or more "routes." Each route is a mapping between an IP address and a client system. The router may also learn route from other routers and by analysis of IP packets. Preferably, the routes known by the router are included in a route table. The router also monitors DHCP assignment of IP addresses to client systems within the network. When the DHCP assignment of an IP address is detected, the router creates a new route that associates the newly assigned IP address and the corresponding client system. The new route is marked so that it may only be overwritten by a subsequent DHCP assignment. The router then updates the route table to include the new route and purges the route table of learned routes that have been invalidated by the new route. In this way, the present invention allows dynamically assigned IP addresses to override learned routes.