An Easy-To-Understand Overview
You've probably heard the term "DNS propagation" before, but aren't quite sure what it means. Don't worry, you're not alone. DNS propagation is a complicated subject, and to fully understand it you need to know how the internet works. In this blog, I'll provide an easy-to-comprehend overview of the internet and DNS propagation.
Let's start with DNS, which stands for "domain name system." A domain name, such as "your-domain-name.com," is an easy-to-remember name that is associated with an IP (internet protocol) address such as 126.96.36.199. While it's easier to remember google.com rather than 188.8.131.52, the internet works on IP addresses. Just like every house has a unique street address, every website is associated with a unique IP address. So when I open up my browser and go to google.com, it's really just going to 184.108.40.206.
How DNS Servers Work
Now let's move on to how your browser knows that google.com is associated to the IP address 220.127.116.11. This is the part where you need to understand more about how the internet works. Your website lives on a web server (which is just a beefed-up computer set up to specifically run websites) in a data center somewhere in the world and the web server will have one or several IP addresses used to find it.
In addition to these web servers, thousands of DNS servers are located around the world. The sole responsibility of a DNS server is to take domain names and associate them to an IP address. These DNS servers store records for every domain and its IP address so that when you type google.com into your browser, it knows to take you to 18.104.22.168, which is the address to the web server where the website is hosted.
Understanding DNS Propagation
So, how does DNS propagation fit into this? It's quite simple actually. When DNS changes are made (like switching hosting providers or switching from an old website to a new one) every DNS server in the world needs to update its records of what IP is associated with which domains. You can imagine it takes some time for every DNS server in the world to update its records. So until they all update to the new DNS/IP information, one might have the old info while another might have the new info.
Let's say we are launching a new site called xyz.com on a different web server and we update the DNS records. Let's also say that the DNS server I use has updated with the new information, so when I go to xyz.com I see the new site. But the DNS server you use hasn't updated, so you go to xyz.com and see the old site. This is because the new DNS updates haven't propagated yet to the DNS server you are using.
And that my friends is DNS propagation. It's simply just the time it takes for all the DNS servers around the world to catch up with the new DNS updates. It's also why all of us web nerds say that it will take one to 24 hours for DNS propagation.
The internet is pretty complex and understanding how it works can be difficult. Things like root servers, caching and authoritative servers will make you say, "What language are you speaking?" I hope this blog was able to take that Klingon language and make it easy to understand.