Quick Routing Review

The subnet mask defines the network and host portions of the IP address for that subnet.
When a packet is to be sent the destination IP and the local netmask are ANDed.
- If the result matches the local network, an arp is issued and the packet is delivered.
- Otherwise it consults the routing table for a gateway to send it through.
Routing tables are built from static routes and/or rip/ospf learned routes.