What do you do when.........
the power goes out?
The cable company needs to perform maintenance?
Your servers Power Supply fails?
Your Hard Drive Fails?
You Max Your internet connection?
You ISP calls you and shuts off your internet for violating the TOS you agreed to, (most major ISP's prohibit using residential services to host websites)
You ISP Shuts off your net cause you get a DMCA
Someone hacks your server and defaces all of your websites, and uses this a stepping stone to your home PC.
If you have answers to all of the above questions, then I think your ready

, this is asuming you have basic networking knowledge, and knowledge of how websites work, DNS etc.
--Peter