I have accounts with 3 different hosts and have decided to consolidate two of them. One of my bigger and highly trafficked sites is on the host im dropping (service is slow and has a lot of outages). I contacted my other host and they told me it will take 24-72 hours after changing the nameservers for everything to trickle down. WTF!!!? Even the crap ass host the site is currently on did better than that, my domains are live and working within 20 mins. I have all the files and DB set up and running smooth, all I need is the domain pointing to the new server without suffering 3 f'ing days of downtime. what would you do?
No way , you cant have that kind of downtime. Possible downtime must be between 0 to 5 minutes for a site transfer.
They are estimating basically. They make the change, but they don't own all the DNS servers that your domain change will have to be propagated to. I can assure you that no one can insure anything quicker than that. I know local ISP's in my area that can sometimes take a week to update their DNS records. So, in a server move, some of your visitors will be cutoff from your new content. Just leave the old sites up for 72 hours.
There is nothing surprising in that. And even though you can access your other sites does not mean they are fully propagted around the world. This is what happens: There are a limited number of master DNS servers around the world. These are the root name servers. They get their DNS info by requesting it from the registrars several times a day. ISPs get their DNS information from these root name servers (this is the trickle down). However, ISPs will cache the master DNS list and update between once a day and every 3-4 days. The reason they do this is to cut down on the number of connections they have to make to the internet. So, let's say that ISP A requests a refresh to its DNS data on Monday morning at 8:00 and refreshes every three days. ISP B refreshes the list on Monday morning at 7:00 but refreshes every day. ISP C refreshes their data on Monday morning at 11:00 and refreshes every two days. You change your host and DNS information on Monday morning at 9:30. Person 1 using ISP A won't be able to access your site until Thursday morning because you made changes after ISP A did their refresh on Monday morning and they will keep those records in cache until Thursday morning. Person 2 using ISP B will be able to access the site Tuesday morning because that ISP refreshes every day. Person 3 using ISP C will be able to access the site on Monday (even though the refresh rate is every two days) because they did the Monday refresh after you made changes. Thus, people using different ISPs or in different geographical areas may not get the same results right after a change. So you may see your sight, but it may not be available to people in Europe until the next day. This is a very simplified explanation. There are a number of things at play. Not every root server talks to every registrar, so there is a period of time they are out of sync. If your DNS data was in one root server, it may not be in the others until they sync. That can cause additional delays. This has nothing to do with the hosting company or the registrar. It is an industry standard. The time it takes can be less, but there is nothing the registrar or host can do to change the delay time. That is an issue with the root name servers and ISPs.