December 22nd, 2011, 09:17 AM
Multiple servers on one IP
This may be an idiotic question but I've done my own web hosting for a lot of years and I have a friend who has been bugging me to set up a larger server and do some web hosting, on a larger scale. By the way, I use Unix, primarily. My skills with this stuff are "reasonable" but I have no idea how you would host a large number of sites - using different physical boxes - from a single IP address (or, even, a few IPs). At the moment we have a Comcast business account and we actually have 5 static IPs (and I've yet to figure out how that works - I'm only using one). In other words, obviously I know how to set up Apache virtual servers. And I know that you can run multiple servers from the same box, or from the same network, using alternate IP addresses. When I Googled this stuff that's all I came up with... What I am asking is this: how does a large web host, like GoDaddy, have a rack of servers (probably thousands and thousands) and they're all accessible via port 80? And, perhaps, this is more of a DNS or networking question. I suppose you could just mount/bind to the different boxes and directories. But I'd like to know how it's done, generally.
Anyway - any info would be appreciated.
December 22nd, 2011, 06:28 PM
Large shared webhosts generally use different IPs for each of their physical servers. Multiple IPs may map to one server, you cannot however map one IP to multiple physical servers.
For high reliability hosting you can use a load balancer or proxy server to distribute requests coming in on a single IP to multiple internal web servers. In this case, the IP points to the single load balancer or proxy server.