Are low TTLs effective in practice? Sounds like a good idea, but what % of users are using DNSs that just ignore it and cache things well beyond what they should?
With a 60 second TTL I see most traffic drop off within 5 minutes, and almost all of it gone within 30 minutes. There's a few stragglers who seem to still be there even an hour after the switch, but by and large DNS TTL does work.
