Changing web hosting companies - HOWTO

6. If everything is working as expected, change the domain name Name servers
Once you have moved your site files and mailboxes to the new web hosting server you are ready to make changes at your domain name Name servers so your site starts pointing at the new place. You should have received the Name server values that you need to apply to your domain name in your new hosting account Welcome email. If you do not have this information you need to contact the new web hosting company support and ask them to provide it to you. There are 2 scenarios here. With the first one we assume that you have your domain name registered with a company different from your current web host. If that's the case, just log onto your account at the company where you have the domain name registered and update the Name servers for your domain name. If your domain name is registered by your current host, ask them to provide you with a way to manage your domain name or just ask them to change the Name servers for your domain name with the values you have received from your new web host.

Once the Name server changes are applied there is 24-48 hours propagation period. During that period all servers around the Internet will refresh their DNS cache and will get the new values for your domain name. During that period some visitors of your site will get to your old hosting server, while some others will go to the new one. Some email messages will be delivered at the old hosting server while some will get at your new web host. That's why you will need the two mailboxes setup described in the previous step. They will allow you to check your email at both places during the propagation period.

Once the propagation period is over all web and email traffic will be directed to the web hosting server.

7. Close your old hosting account if needed
If you no longer need the old hosting account, you can ask your old web hosting company to close it and provide some compensation if legible. The other option is just to leave the old hosting account to expire. However, if you are billed automatically you need to contact the old web hosting to cancel the account.