So I'm looking at moving my companys outsourced web/email internally. One question that I have is what will be the expected downtime for moving the web and email servers to a different ISP(our class C). I know this has to flow through all the root DNS servers to make the IP changes but wasn't sure how long this would take to change from the old IPs to the new IPs. Hours? Days?
Also any go recommends on email server software(You should know my stand on OS by now)? We are currently using iMail which we will probably stay with but never hurts to try something new/better.
the last time i switched my company's(previous comany) it actually took less than 24 hours. switched it 5:30 in the evening on a thursday, it was good to go at 10am or so the next day. I was quite suprised actually.