There are several tricks you can use for DNS failover, but it's not generally regarded as a reliable option. DNS caching has all kinds of awkward gotchas. You c

There are several tricks you can use for DNS failover, but it's not generally regarded as a reliable option. DNS caching has all kinds of awkward gotchas. You could also host a reverse proxy somewhere reliable which just forwards things to you over the appropriate connection If you need reliable hosting with multiple providers then you can get your own AS number and use BGP routing to provide failover. But that's more expensive by one or two orders of magnitude.