DNS propagation – What is it?
DNS propagation is a complex process involving the update and spread of new modified information across the network of servers. Whenever you make a change in your DNS, for instance, create a new DNS record or edit an existing one, it is going to be saved in the authoritative DNS name server.
However, the network contains numerous DNS servers, such as the recursive ones, which are spread in different geographical places all over the world. Therefore, each server on the network has to receive the updated changes to function correctly in the process of DNS resolution.
The time required for distributing the changes to all of the different recursive servers is the DNS propagation.
How does it work?
DNS changes and modifications are needed in various situations. For example, you may want to migrate to a different hosting provider or renovate your website, or maybe you want to add a brand new service (email, FTP). These are just some of the various actions that would demand making adjustments, adding, and removing DNS data (DNS records).
Your DNS administrator or yourself is going to complete these tasks straight to the authoritative DNS server. Then when everything is set up there, the process of updating and spreading through the network has to begin. Each DNS server on the globe has to obtain a duplicate of the new DNS information.
That is why it should not shock you if some of your users receive the new version of your website and others who are located in a separate country get the previous version. However, as we mentioned, DNS propagation is a process, and it needs time to propagate completely to all of the DNS servers.
What affects longer DNS propagation?
DNS propagation could take a long period of time. So, that depends on several factors:
- The TTL values of the DNS records. The various DNS data has limited time established, determining how long servers should store the DNS records. So, the servers are not going to seek the DNS data until the TTL expires.
- The TTL values from ISP’s servers. Internet service providers (ISP) configure their DNS in their own way. Typically, their TTL values are higher to optimize the usage of the resources and store the DNS records of the domains for faster response to DNS queries. For that reason, their TTLs should expire, and then your new DNS modifications are going to propagate.
- The devices’ DNS cache. The computers of your users also have a DNS cache, which stores the DNS records of the domains they visit. So, until the TTL expires, some users could receive the older version of your website. They could delete their DNS cache or wait for the TTL to expire to reach the updated version of your website.
- DNS changes in the highest hierarchy level. You probably know that the DNS servers have a hierarchical structure. For that reason, when changes are completed on the root servers, the DNS propagation is going to take more time. At that level, the TTL values are usually higher.
Suggested article: Why should you implement Dynamic DNS?