I have my computer running an Apache Webserver on Ubuntu Linux. My friend is also running a mirror of the site on Apache as well on a Windows system. I want to set it up so if my computer goes down, it can redirect to his server. I have no idea how to set this up, and we both have dynamic IPs, but they don't change very often, once a month maybe. I'm using EveryDNS.net for my DNS settings with a client updating the IP every two hours. Any advice? I'd like to stick with free DNS servers if possible, but may consider switching to a low cost one if neccessary.
I suspect this is more complex than it first appears. Probably something to do with setting up some sort of failover DNS - but I bet it's not easy to do. You'll notice that the vast majority of websites don't do anything like this - just the really, really big ones.
My take on this is that 'you're not amazon'. The world won't end if you're down for an hour or two. If the site was of any consequence, you wouldn't be hosting it on a dynamic IP for example (please - I don't mean to imply you're site's not fine - just put some perspective on it. This is my attitude with most people's sites, not just yours).
You're trying to limit downtime using a complex solution. There's far easier ways to do that. The first thing to do is find a solid host. Decent hosts these days basically never go down. Second is to make regular backups and archives. That will involve far less money and effort and are well known solutions, vs. the technical complex solution you're trying to employ.
Seems to me the simplest thing is to re point the DNS but it takes time for that to propagate and might cause more harm than good if you're only going to be down for a short period of time. I'd certainly never consider hosting a "true" server at home unless it was strictly for personal use. Just the electricity alone used per year cost more than shared hosting, not to mention the time spent managing it and updating the IP as you stated. For less than $200 bucks a year you can have shared hosting, with support and not worry about all that. For that matter Microsoft will host it for free if money is an issue. Just my 4 cents worth.