This image shows how this topology distributes Oracle Application Server components over multiple computers and tiers. When the client makes a request, the request is routed by the load balancer to an available Web server. The Web server then forwards the request to an Infrastructure configuration, or sends it beyond the intranet firewall to the database. Access to the computers in each tier is guarded by firewalls. This distributed topology enables you to scale the number of computers in each tier (to increase performance and availability) without affecting computers in other tiers. This illustration is further described in the surrounding text.