I Recently moved the domain www.global-video-pages.com from a server in Germany, to a server here in South Africa, It took about a week for the site to get back online. Why so long?
It was because of DNS Propagation.
So what is DNS propagation?
Once you make changes to your domain with the registrar you purchased your domain from, the changes will take anywhere from 5 minutes to 72 hours for propagation to occur depending on your ISP and how often they update the DNS records.
Domain propagation is the process of your registrar handing off the changes of your domain to root DNS servers, ISPs acquire records from the root servers, ISPs to other ISPs and so on until you see the changes reflect on your computer with your internet service provider. Some service providers update their records more often than others and receive changes faster. As a result of this, often you will not be able to get to your website by its' domain name but a friend can. Simply wait out until the changes propagate to your ISP.
My blog was down yesterday and the night before. I wanted to change the IP address of my domain. Gitui.com. After about 48 hours I gave up and chaged it back to the old IP address, and it worked fine. Because of that I knew that the DNS propagation was not even started. Because all the records still pointed to the old IP address.
That is briefly what DNS/Domain Propagation is. It will affect your site and all your emails.
They told me about the propagation. I thought they were sucking it out of their thumbs. Now I understand whats happening.