Understand the meaning of propagation
Basically, the definition of propagation is the time it takes for the domain to be resolved to the IP destination that has been set. When you add a new domain to the DNS control panel, it takes time for the DNS to be perfectly propagated on the internet.
Where does the Root Name Server receive information from?
The root name server will query "domain registrars" several times a day. The root name server will collect this information from many existing registrars and update their master records. Now your ISP must access their Root Name servers and update their DNS records that reside on their local DNS servers. This process is fully automated and most ISPs will check for Root Name server updates every 24 hours. Be warned however that some lame ISPs will delay this process for 2 to 4 days in some cases. If that happens, it will undoubtedly cause additional confusion as everyone will reach your new account on our servers except you. This is because your ISP has not updated their DNS records and or has not cleared their DNS cache which means they will still be pointing your domain name to your old servers. If it is a new domain that you have registered, then you will receive a blank 'Site Not Found Page'.
DNS Cache and Your ISP
In a large number of cases, this is a result of ISPs "Not" configuring their servers to "Expire" DNS cache records at appropriate intervals. Unfortunately, this adds additional confusion for their clients and especially those trying to point their domain names to new servers.
The DNS propagation process is not limited to ISPs. The Internet itself has to update/delete its DNS cache as well. When we say Internet, we mean the intermediary "access points" that you acquire before reaching your final destination. For the most part, these intermediate access points consist of "Internet Routers" and "Internet Caching Engines". These too, maintain their own DNS cache which helps them in routing traffic/resolving URLs to the correct destination IP. Don't worry as Internet routers are usually faster at clearing their DNS cache than ISPs.
What to Expect during the 24-hour propagation period
In most cases, the propagation process will take at least 48 hours to complete. The first thing that happens is that the "World Root Name Server" will check all the various "Domain Registrars for updates". Once the root name server has done this processing, the rest is up to the many ISP providers who "should" update their DNS records (at least every 24 hours), but some of them do not.
DNS propagation actually happens in just a few moments. But for the effects to be visible worldwide and across multiple ISPs (internet service providers), it can take several hours - up to 24 hours. But the quickest way if it's still cached is to restart your modem or router, or restart your computer.
