So you got a new website or you moved your existing website, but your not seeing the new site when you updated your domain name and your being told it can take up to 72 hours to propagate?
What is propagation and why does it take up to 72 hours?.
Let’s imagine you live in Colorado Springs, CO and you just have changed the nameservers for your domain that is hosted in Salt Lake City, UT.
When you open your website in a web browser, your request is not going to the hosting server directly, it has to pass through your ISP and several other ISP nodes first. So your computer starts by checking local DNS cache on your actual device/computer, then the request is sent to your local ISP (say Comcast). From there, the request goes to the upstream hub in Denver, then connects to their backbone. After that, the request is sent to the first receiving point off their backbone, in this case Qwest in Cedar City, UT and ultimately, to the web hosting server ISP backbone in Salt Lake City, and finally through their own network stopping on the physical server that hosts your website. Here is an example of the request trace – the number of ISP nodes and their location when I make the request to view your site:
Traceroute to jaydenhomescolorado.com (22.214.171.124), 64 hops max, 72 byte packets
1 10.0.0.1 (10.0.0.1) 2.784 ms 2.127 ms 2.150 ms
2 126.96.36.199 (188.8.131.52) 12.292 ms 12.477 ms 12.275 ms
3 ae-207-sur02.cosprings.co.denver.comcast.net (184.108.40.206) 38.011 ms 19.889 ms 13.024 ms
4 ae-23-ar01.aurora.co.denver.comcast.net (220.127.116.11) 16.801 ms 29.757 ms 17.757 ms
5 be-33652-cr02.denver.co.ibone.comcast.net (18.104.22.168) 17.251 ms 14.568 ms 15.110 ms
6 hu-0-12-0-7-pe02.910fifteenth.co.ibone.comcast.net (22.214.171.124) 15.099 ms 14.900 ms 14.737 ms
7 dvr-edge-13.inet.qwest.net (126.96.36.199) 15.206 ms 24.731 ms 14.916 ms
8 63-232-104-62.dia.static.qwest.net (188.8.131.52) 28.008 ms 26.328 ms 24.851 ms
9 162-144-240-143.unifiedlayer.com (184.108.40.206) 28.473 ms 29.519 ms 30.421 ms
10 162-144-240-51.unifiedlayer.com (220.127.116.11) 39.625 ms 49.962 ms 49.773 ms
11 server.ilgmwp.com (18.104.22.168) 30.087 ms 25.724 ms 28.681 ms
As you can see there are 11 servers that have to have the proper update in their DNS system to get everything synced.
Each of the ISP nodes (server) checks its own cache to see if it contains the DNS information of the domain. If it is not there, it looks it up and saves it in order to speed up the loading next time and to reduce the traffic.
That is why the new nameservers will not propagate immediately – ISPs have different cache refreshing intervals, so some of them will still have the old DNS information in the memory.
This is also why people/devices that have not visited to your site recently will see the change quicker than, say you, which is there daily or several times a day. It's also why one device on a network will effect all the other devices on that same network.
So that's why why we state "72 hrs" to give everyone time to get caught up.
NOTE: to make sure it is not your computer cache that has the outdated information, we recommend clearing the cache of your browser and flushing the DNS cache after the DNS change.