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We just completed a site redesign and the new version was deployed to a different server. The domain name entry was updated and everything works fine. But some users who still have the old DNS value cached are getting the old site. This is expected to happen for a short period. But I want to know what things we can do to minimize this in the future. I'm thinking of tips involving TTLs and things.

Unrelated: It seems that once something is marked community wiki you can't undo it. It was my mistake and I'm not sure if it's good or bad.

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I'd recommend changing the TTL to something low a couple of days before you change DNS entries. That way, hopefully, when you change the dns the site will go live much quicker for most people.

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Yeah that's what I was thinking, but didn't know if that was a "best practice" or if it had any downsides. I'm just a lowly web dev who has been coerced into doing sys admin work ;) –  Marco Jan 28 '10 at 19:01

Last time I needed to do this, I arranged for the old server to transparently redirect all traffic to the new for the TTL period following the DNS record change.

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There are a couple of reasons I can't do this. The domain is the same, it's only the ip that has changed. So if their cached dns is still sending them to the old ip, where would I redirect to? Also, there are other small apps running in virtual hosts on the new server. So hitting the ip doesn't give you the main site (and probably shouldn't). –  Marco Jan 28 '10 at 19:04
    
What the parent is suggesting is to keep the old IP live during the transition (Either put it on the new server or have the old server port-forward). This (in combination with reducing the TTL a few days before the migration) is generally the best way to go as some ISPs DNS servers don't respect TTL values. –  voretaq7 Jan 28 '10 at 21:47

As there are many systems that ignore TTL I suggest that on the original server you kill the site and replace it with a redirect using the IP address of the new server. That will ensure everyone ends up at the correct place while waiting for the cached DNS entry to expire and be updated. After a week or so you should be able to remove the original server.

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