|  |  | Summary

In this chapter, you learned that:

- internetworking functions of the network layer include network addressing and best path selection for traffic
- all devices on the LAN are required to look at an ARP request, but only the device whose IP address matches the destination IP address carried in the ARP request must respond by providing its MAC address to the device that originated the request
- when a source is unable to locate the destination MAC address in its ARP table, it issues an ARP request in broadcast mode to all devices on the local network
- when a device does not know its own IP address, it uses RARP or BootP
- when the device that originated a RARP request receives a RARP reply, it copies its IP address into its memory cache, where it will reside for as long as the session lasts.
- routers, like every other device on the network, send and receive data on the network, and build ARP tables that map IP addresses to MAC addresses
- if the source resides on a network that has a different network number than the desired destination, and if the source does not know the MAC address of the destination, it will have to use the router as a default gateway for its data to reach the destination
- routed protocols direct user traffic, whereas routing protocols work between routers to maintain path tables
- network discovery for distance-vector routing involves exchange of routing tables

The next chapter discusses the functions of the transport layer.