I recently started use dedicated server, and I am planning to host other domain names. Since I will be using SSL, I need to have mulple ips. My question is "why a server is capable of having multiple IPs?" I believe my rented server only has one ethernet connection. The other question is "Do I have to tell my hosting company which directories these IPs point to?" I know these questions sound a little stupid, but I could use some advice!

Networking is hierarchial and independent of any subnets below it. That means that your ISP doesn't need to know the private IPs you assign clients to your server: it doesn't care. All it "sees" are packets traveling to and from over the gateway IP address(es) its server supplies your server. Your server takes care of the routing over its own network. If you turn your DHCP server off it acts like a switch and then the server ABOVE it has to assign IP addresses to the clients for these to communicate. You still don't need to tell it what IP addresses to use: That server would then tell YOU what IP addresses were available.

Don't confuse a hardware connection [ethernet] with a logical connection [ip address]. A single nic can have multiple bindings either dealing with different protocols and/or multiple ip addresses. Since you will be doing your own hosting I am not sure why you would be concerned about the present hosting company. Golly gee wilerkers everyone. Learn to Internet Search