Unix: Getting from here to there (routing basics)
What is routing? It's the set of rules that govern how you make connections to other systems. Any time you make a connection from one system to another system -- whether you're sending email, transferring a set of files or logging in with ssh -- you're routing. And, since most connections aren't direct (in other words, they're travelling through one or more system en route to the target), most of the time you're going to be crossing a router -- or maybe a long series of routers -- to get there.
To view the routing table on a Linux system, use the netstat -rn command. The output of this command will tell you how connections you initiate are going to be handled. The routing table on most Linux systems will look something like this: