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Is it feasible to switch DNS A records to point to a backup provider in case of failure?

Instead of relying on one provider/datacenter.

I know there is a lag due to ISPs caching the records, but it's at least something.

Is there a better way to create redundancy by switching to a server in another datacenter/provider?

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Your proposal would work, as long as your SOA record had short enough TTL's.

It isn't ideal (i.e. it isn't how the big companies like Google, Facebook, etc. manage multi-homed sites), but it is probably the cheapest method.

The other approach would be to host a very small site on Amazon AWS that just redirects... so you have www.yourdomain.com (on AWS, that then redirects to) www2.yourdomain.com (in times when your primary ISP is working) or www3.yourdomain.com (when it needs to go to your alternate).

The AWS code could be set to auto-update when it detects an outage, or you could tweak it, and it would have instant effect.

Of course, if money isn't a concern, there are many more elegant solutions -- I did sense that you wanted to have the most economical approach, though.

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  • Interesting, I've seen that www3 type of redirect before but I didn't think of it in this situation. The problem with that though is that you have to make sure the redirector is always working, and that people don't bookmark the nodes directly.
    – Sarke
    Nov 16 '15 at 6:18
  • That is true. You could use some fancy iframe coding or similar to handle the bookmarking issue... there may be some javascript that could fix that, too. As for the redirector working -- that is also true. It wouldn't have to do much in the way of heavy lifting, which makes the monthly cost rather small compared to running the whole site on AWS.
    – Kris B
    Nov 16 '15 at 6:30
  • The SOA record has nothing to do with the positive TTLs of other records within the zone. The default TTL field was redefined as the negative caching duration awhile ago.
    – Andrew B
    Nov 16 '15 at 9:56

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