What does DNS propagation mean?
Whether you manage your own website or have a team of professional’s manage your site, you may have run across the term “nameserver”, aka DNS. However, you might not have any real understanding of what one is or how it works. As it turns out, knowing a little about this concept can come in handy for managing your site.
Put simply, a nameserver helps browsers make connections between URLs (Uniform resource locator) and websites. They’re incredibly important, as, without them, we would have to memorize IP addresses in order to access websites.
When you update the nameservers for a domain it can take up to 24-48 hours for the changes to take effect or propagate. This lifeless dead period where you cannot get to your website is called DNS propagation.
In other words, it is a period of time the ISP (Internet service provider) nodes across the world take to update their caches with the new DNS information of your domain.
Due to DNS caches of different levels, after the nameservers change, some of your visitors might still be directed to your old server for some time, whereas others can see the website from the new server shortly after the change.
Why does it take so long for the DNS propagation to complete?
Let’s imagine you live in Tallinn Estonia, and you just have changed the nameservers for your domain that is hosted in Phoenix, USA.
When you open your domain in a web browser, your request is not going to the hosting server directly, it has to pass through several Internet service providers (ISP) nodes first.
So your computer starts by checking local DNS cache, then the request is sent to the local Tallinn ISP. From there, the request goes to the upstream provider in Stockholm, then connects to the ISP in Hamburg, Germany. After that, the request is sent to the first receiving point in the USA – New York, NY, and ultimately, to the ISP in Phoenix, AZ.
As you can see from the information above, there are lot’s of databases that need to get populated with your new DNS information before your domain will be bona fide!
Rest assured this has been going on since the Internet first started and while no one likes their website down, it will not be down for long.
Kinsta.com has a full blown article regarding DNS and NameServers here!