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33 lines
1.3 KiB
Plaintext
33 lines
1.3 KiB
Plaintext
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#!/bin/cat
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$Id: FAQ.TTL.txt,v 1.1 2017/05/03 22:27:45 gilles Exp gilles $
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This documentation is also at http://imapsync.lamiral.info/#doc
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=====================================================================
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Imapsync tips about TTL when changing name resolution of hosts
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=====================================================================
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Why decrease the TTL (Time To Live) delay in DNS configuration, down
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to 5 minutes?
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A small TTL is not mandatory, it's safer and more easy to work with when
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migrating.
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It's about how long it takes to be sure the users are using the new
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imap host, and how long it takes to be sure all new incoming messages
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are going right now at the right place. Will you shut down the old
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server just after the resolution change? I guess you won't and you'll
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be right.
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The TTL is just a value, very well supported by machines, with a
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little name resolution supplementary work for them when it is set to a
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small value like 5 minutes, but it's a tremendous comfort for migrator
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people like us.
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Be sure to wait 24h after this TTL change before changing any
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resolution since the TTL change has to be propagated as well. After
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the migration done, no problem to set back the TTL to 24h or more. If
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you can't decrease TTL under 4h or even 24h, it's ok anyway, imapsync
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can sync the new messages dropped in the old server.
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