IP Connectivity

IP Connectivity is the largest single domain on the CCNA 200-301 v1.1 exam, and it is the heart of what a router actually does. Domain 1 taught you that a router is the device that moves packets between different networks. This domain answers the next question: how does a router know where to send a packet?

The short answer is the routing table. Every router keeps a list of the networks it knows about and, for each one, where to send packets destined for that network. The router builds that list from three sources:

1. Connected routes - networks the router is physically plugged into.
2. Static routes - routes a human typed in by hand.
3. Dynamic routes - routes learned automatically from other routers by a routing protocol such as OSPF.

This chapter walks through all three, then explains how the router chooses between competing routes, and finally covers First Hop Redundancy Protocols (FHRPs), which keep end hosts working when their default gateway router fails. Expect the exam to test this domain with configuration questions, show output interpretation, and “which route will the router use?” puzzles. Every one of those is covered below.