Most routing in pfSense is handled transparently, and, as a result, we tend to take it for granted. A pfSense router will know where to send traffic between two networks if both networks are connected to pfSense. If it doesn't know where to send a packet, pfSense will send it, by default, to the gateway, which in most cases is the WAN interface. Thus, if we request Google's home page, pfSense's routing daemon will realize that Google's IP address is not on any of the local networks and send the request through the default gateway.

There are cases, however, where the destination network is a local network not directly connected to pfSense, and not reachable though pfSense's default gateway. If there are only a few such cases in our network topology, then we may be able to define static routes to cover them. Otherwise, we might have to consider using a dynamic routing protocol to enable our routers to learn the network topology.