No matter if DNS resolves fine or not, the packets still aren't gonna route over a provider that doesn't announce those blocks to the net. You can run two together to provide no single point of failure. Today there are 150,887,000 people connected to the Internet. We currently have a net backbone of 2 DS1s. We have several IP blocks from each provider.
Outbound traffic is done with static default routes.
It does not run on the routers or servers. 2 to each provider. 2 DS1s will terminate into each. Click the above link to learn more and get free research. Click the above link to learn more and get free research.