|  |  | Overview
A router is a type of internetworking device that passes data packets between networks based on Layer 3 addresses. A router has the ability to make intelligent decisions regarding the best path for delivery of data on the network. In this chapter, you will learn how routers use a Layer 3 addressing scheme to make forwarding decisions. In addition, you will learn how devices on local-area networks (LANs) use Address Resolution Protocol (ARP) before forwarding data to a destination. You will learn what happens when a device on one network does not know the MAC address of a device on another network. You will learn that Reverse Address Resolution Protocol (RARP) is the protocol a device uses when it does not know its own IP address. Lastly, you will learn the difference between routing and routed protocols and how routers track distance between locations. You will also learn about distance-vector, link-state, and hybrid routing approaches and how each resolves common routing problems.