I am attempting to formulate a Disaster Recovery strategy for our company website and would like to know if the following is even possible theoretically or practically?

If I ask our Domain registrar to set our Domain DNS TTL to 3600 permanently, then host our website on a second server that mirrors the primary server will I theoretically be able to switch from primary to secondary in 1 hour limiting our website downtime.

Any advice would be greatly received.


That should work fine. Operating systems and browsers may cache DNS lookups, so users may see the downtime as longer. (More info here: http://dyn.com/web-browser-dns-caching-bad-thing/).

You could reduce the TTL even further, down to the time it takes your mirror to catch up with changes on your main site.


Most providers won't let you permanently set a low TTL because it significantly increases the load on their servers. Others charge more for a more dynamic service. So it is worth checking that they will do it before you count on it.

  • Hi James,I've checked with ours (123-reg) who seem happy to do this permanently so does that mean you see no other problem with the idea?
    – David Clee
    Feb 1 '12 at 14:24

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