@Tacroy said:
Hosting providers always seem to say it'll take up to 24 hours to make DNS changes; this is so pervasive that I think it's probably a CYA move, because if they give an actual estimate (like your TTL or something), they'll get picky business customers complaining when the changes haven't taken effect exactly at the estimated time.
Also, 24 hours is long enough that you probably won't be willing to make changes willy-nilly, which might decrease the load on their servers or something.
I work for a hosting company and say exactly the same thing to customers - simply because you DONT KNOW what configuration an intermediate router/DNS server has on it (Crappy home broadband routers :@) .Give an estimate too low and the customer is on phone asking why there site doesn't work when you said it would; give an estimate too high and the customer goes away satisfied.
Additionally, most websites and DNS providers default to 86400 seconds as the ttl (eg: thedailywtf.com) so upto 24 hours
is a fair reply to make.