The examples in this book use "Router" as the router 's name. That's fine for examples, but a bad idea in real life. Eventually, a router should be given a name. To set the router name to "Sphinx", use the hostname command:
Router(config)#hostname Sphinx Sphinx(config)#
The router instantly responds by updating the prompt to reflect the new router name. The name can be up to 254 characters long, but don't use a name so long that you can't type it comfortably.
It's a good practice to follow a naming convention for your routers. With a logical, consistent naming scheme, it's easy to remember a router's name, or guess the name if you've forgotten it. For example, let's say that your router names all start with "rtr", followed by the city initials, followed by a number. Then, late one night when you're staring at a blank terminal screen trying to remember the name of the backbone router in New York, you can type rtr-ny-01 and be reasonably confident that you've guessed correctly.