When you update a DNS record, notification of the change is sent up to the
root servers for the TLD of your domain name and then that update feeds
back down to all the servers around the world based on TTL.
The problem is that many ISP's implement localized DNS caching within
their own networks and pull live DNS updates on their own schedules
instead of TTL settings. In plain English, this means that the DNS
information may be updated and correct but some ISPs may have old
cached data pointing back to the old information that sticks around for
a few days longer until their servers decide to update the information.
To complicate matters further, most PCs also cache DNS routing information
locally as well and if you frequently visit a site and that site changes it's
IP address, your computer may still try to go to the old IP address even
though anyone new visiting the same site would correctly go to the
new address. This can of course be changed by flushing your local DNS
cache or by adding a route to the new IP in the host file on the computer
of the visitor who is visiting that site:
When transferring sites to a new server, I often duplicate the site on the
ipconfig /flushdns (Windows XP/Vista command to flush DNS cache)
new server and setup a mirroring update to keep the old site in sync and
then go ahead and update the DNS information on the OLD server
to point to the NEW IP address on the NEW server so that
connections start going over to the new server and those who have old
improper cache data can still see the site on the OLD server.
After a few days, I go ahead and update the DNS servers themselves
for the domain and then cut the OLD site.
By doing it this way, there is no appearance of downtime and everything
is seamlessly transferred from the original server to the new server.
If you want to be sure you are connecting to a specific server, you can
put the domain and www address in your local hosts file:
Anyway, taproot, to answer the question in your post directly, the issue
C:\Windows\System32\Drivers\Etc\Hosts (Windows XP/Vista)
/etc/hosts (Linux / Unix)
you are experiencing is common and is natural and is caused by the
update transitional period where some ISPs have live DNS data and others
have old cached data and has more to do with how the worldwide DNS
system works and isn't anything to do with your server or what you did!
Everything will sort itself on it's own in a couple of days!