Is there a service which allows me to add a secondary DNS name which acts like a fail-over server?
If my primary webserver was to fail (along with its DNS) the secondary DNS server would redirect users to an offline status page instead of showing users a timeout message.
Are there any free services out there?
Apart from free hosting (I currently do not have the capacity to purchase a second server.)
Be careful! Multiple DNS servers mean "any of these servers can be queried for the domain information", not "if the first fails, try the next".
You need something with a bit more intelligence. Unfortunately, there's no Free, Easy and Reliable way of doing it.
If you happen to have a load balancer, it may be possible to configure it with a 'failure' page.
What you're asking for is actually a function usually reserved for HA type setups (hardware load balancers, multiple servers, etc).
To return a different DNS resolution, you would first have to identify that the service was unavailable. This can be done if you externally host your DNS with someone like ultradns and pay for their sitebacker service (it's not horribly expensive, but it is not free). I am not aware of any other services/registrars that will perform this function for free.
Otherwise, you would have to funnel your requests thru a host that was at least reactively aware that the web server was down, and route the request to somewhere else. This method has the drawback that if it's your internet connection that's down, you're still boned. Depending on your requirements, you can likely get by with some pretty low power machines for this setup.
This can all be done fairly affordably, but! it will require at least a moderate investment by your business. If the business chooses not to spend some $$$, then the business needs to acknowledge that sometimes, their customers will get timeouts. Personally, I have almost 300Mbs bandwidth across multiple ISPs and datacenters, and still get the occasional timeouts due to...say...both ISPs deciding to do unannounced router updates on the same night.
It really is as simple as clearly stating that more uptime = more $$$. Proper design and configuration has some part as well, but remember the triangle: cheap, fast, good...pick 2.
You can host your status page in Blogger.com, wordpress.com, or another weblog provider . I've seen a number of sites using this approach.
Some idea's on how to achieve this...
Linnode/Slicehost allow you to do IP failover to a second host if you purchase two VM's from them.
Have www.domain.com hosted somewhere that is highly available (such as shared hosting package with a provider that guarantees 100% uptime) that has a background process running that pings www1.domain.com. If www1.domain.com doesnt respond, it updates the forwarder page to goto www2.domain.com.
Have a keepalive script that dynamically updates your DNS if www1. goes down.
Not free but pretty darn low really. Try DNSMadeEasy.com, where their business package gives you DNS failover for 3 A records and top notch DNS hosting for $59.95/year. Think that's not too bad a deal.
