Any disadvantage to short DNS TTL?
closed as not a real question by John Gardeniers, Chris S♦, Sam, Zoredache, Jim B Jan 28 '11 at 22:24
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Your DNS should not change very often in the first place. Many DNS server do not honor your TTL "request" and impose their own policy. If you're going to make a chage, set the TTL lower weeks before the change. Normally having a long TTL helps reduce load on your authoritative server(s) and adds a bit of time to clients accessing your site. I commonly use 3600, or even 36000 depending on the situation.
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Higher TTLs mean fewer DNS lookups, which probably will translate in to lower "costs" for you and whoever's hitting your DNS. (less round trips)
That said, very low TTLs can be useful for infrastructure.
If you've got a 'floating' backend infrastructure DNS name (eg. puppet.sample.com) that you move from one box to another for High Availability and it's only your systems that need to honor that record, then low TTLs can be quite useful.