'DNS propagation' is a term to describe the updating of information across the Internet. It takes two forms: changes to your DNS Zone and changes to your WHOIS information.
A change to your DNS Zone information typically affects only a handful of servers, and completes much more quickly. However, the WHOIS is the master record which tells every DNS server in the world the server for your domain. A change to your WHOIS information (such as updating the ADMIN-C in your control panel) can take up to 72 hours to propagate fully.
Customers often call the 123-reg support centre to say that they can't see their domain names straight after ordering them, or just after a transfer between providers. After either of these two events your domain name/website may not be visible for up to 48 hours, mainly because millions of DNS servers need to be updated with the new information.
What is Propagation and How Long Does it Take?
Name server changes usually take 24 to 48 hours to fully start working. This period, called propagation, is the projected length of time it takes for root name servers and cache records across the entire web to be updated with your website's DNS information. Because of propagation, not all visitors will be directed to your new name servers on your new hosting account; some visitors will continue to be directed to your old name servers on your old hosting account until propagation is complete.
How quickly visitors are directed to the new name servers depends on their physical location, internet service provider and some luck; it is not something HostGator has control over. Once propagation is complete, your site will appear on our server and your email will be fully functional.
There is no definitive way to tell when propagation is complete. During the first 48 hours, even if you are able to see your site on the new server, your next door neighbor might still be seeing the site on the old server.