DNS Propagation Explained
DNS propagation is how long it takes for an update to the nameservers of a domain to take effect – usually between 3 – 72 hours. This is the period of time it takes ISPs (Internet Service Providers) to spread your update throughout their caches around the world. Due to DNS caching some website visitors may see an old page during this time, while other users may see the new update immediately. Lets take a moment to look at why this change can take so long and a way to somewhat bypass the propagation period.
Why Does Propagation Take So Long to Complete?
This is a very common question from anyone who has ever hosted a site on the internet. When you use a web browser to access a website, your query is passed off from node to node until it reaches the destination server. Each one of these nodes is typically owned by an ISP (Internet Service Provider) and they may update their individual caches at different times.
Essentially what happens is the Internet has a number of megaservers, called Root Nameservers, that store all the information on which IP a domain points to. These servers are owned primarily by large corporations (such as Verisign) or government entities (such as NASA or the US Army). These servers store the data in a cache, and update their caches at certain intervals by checking the neighboring root nameservers if they have any updates.
Since there are different groups running the servers, their updates are performed on different schedules. If we update your DNS at 12:00 PM on a Monday, root server A may run an update at 13:00 PM, but server D might not run their update until midnight. If your website is connected on Server D, that means server A won’t get updated until 13:00 PM on Tuesday, since Server D wasn’t updated on Monday. In this way the servers check as many of their neighbors multiple times a day, but can only update if their neighbor has updated. This means it can take upwards of 3 days for all the nameservers to be accurate. It’s unfortunately a process that cannot be sped up, but there is a way to bypass the DNS propagation if you have not already changed your nameservers. Let’s take a look at how this can be achieved. We’ve created a handy image for you to review that visually explains this process below.
How to Bypass DNS Propagation
This method ONLY works if you have NOT changed your nameservers during a website transfer. If you have already changed your nameservers it’s best if you wait for propagation to complete, as making multiple changes could delay the propagation time. You can check the status of a domain’s propagation by using a wonderful online tool called whatsmydns.net. To reduce/bypass propagation time you simply need to do the following:
- Change the TTL (Time to Live) for the DNS records you would like to change to a value such as 300 seconds
- Wait for the previous TTL value to expire
- Change the DNS record A record
- Allow the TTL value to expire to confirm the changes have taken place
- Change your nameservers to your new host
Once this process is complete, your domain should begin resolving the same content regardless of if the user’s browser is pulling the site up from your old host or the new one.