This is one of the most frequently asked domain questions.
Problem
The problem is clear, you have changed nameservers but when you open the domain it still points to the old address.
How? The thing is, DNS systems are VERY slow. In order not to overburden those systems, they refresh for a certain period of time, that is, they look at the domain record and make changes in their database if there is a change.
That's basically the whole problem. There is a time in DNS that is set for how long the servers will look at your domain's DNS, but you cannot check it on shared or cloudflare.
On cloudflare, that time is much longer, so in the situation when you switch to cloudflare, it goes very quickly, but if you change dns FROM cloudflare to some others, then that change takes quite a while.
How can you measure what is happening there and how far it has come after the change.
There are a couple of sites that we use to control propagation and they are:
intodns.net - checking if everything is OK with DNS
dnschecker.org - we check DNS propagation.
When you open dnschecker, you will see a globe with dots on the right, and these are DNS servers. All of those DNS servers have a record of your domain (yes literally all of them).
Scenario
You changed the nameservers on the domain say at 10 in the morning. Take a look at dnschecker it points to the old ip address of your hosting.
(You can request the IP address of your current and future hosting from support or type "ping hostname/cpanel link" in the command prompt and you will get the IP)
It means that nothing has been done yet. After 1 hour, you can see that two or three have changed the IP address to a new one, joy begins and a better mood begins when you check it in a few minutes and those three changed to the old one, but some new ones changed to the new one. What is happening now? The point is that DNS servers communicate with each other and synchronize themselves. Those who were the first to change changed, and later on the second synchronization they synchronized with their partner dns servers and returned the old values because they thought they were new, and these old ones saw the new ones and changed them, so now we are waiting for others to see the new ones and synchronize with the others.
That's pretty much how it works, it's quite confusing at first but it's a simple matter. DNS propagation is a game of deaf phones literally and you have nothing else to do but wait until all servers change their IP to a new one, that is, your new hosting.
How long does it take?
It can last up to 30 minutes if you're lucky, and it lasts up to 48 hours (yes, literally two full days).
Can it be sped up?
It can. To delete dns/hosting/domain from the dns hosting you are leaving. That can speed up the process a bit.
DNS checker shows a new server but I see the old one?
This is where a new problem arose. In addition to those DNS servers that you see on the map, there is a DNS server of your Internet service provider, so there is DNS caching in your computer.
If this is the case with you, you can, for example, turn on mobile data (NOT WIFI) on your mobile phone and open the domain, you will see the new hosting on the phone, while the old one is on the computer.
How can you solve that?
Well, this is already quite simple. For those who are lazy, try restarting the computer and rest until the computer restarts. For those others who do not like to turn off the computer, the procedure is:
open command prompt (start type cmd and enter (win7,8,10)) and type "ipconfig /flushdns" without quotes and press enter.
Then open the domain again in the browser. If the problem is still there, then clear the cache from the browser and type the above command again.
If the problem is still there, clear the cache from the browser, type the command above, restart the modem and the computer and the problem is solved.
