Through time, all businesses require changes to DNS records. But even you make such modifications fast, they won’t be visible immediately. This can be a bit frustrating, especially in urgent cases. Besides, taking too long could point to an issue. In any case, you will have to check how it is going.
Basics of DNS propagation.
DNS propagation is the time that it takes for DNS changes to be fully updated across the Internet.
Remember that modifications to DNS records can be made only on the authoritative DNS nameserver. And currently, most networks are really large. They integrate many servers, machines with different purposes, and all of them can be spread globally.
With this image in mind, you can easily understand why changes, small or big ones, take time to be completed. They have to be updated on plenty of machines!
Additionally, the process can face obstacles that can delay it even more. For instance, the DNS cache of the network’s servers. It totally contributes to making the network more agile, but it can delay the DNS propagation. They keep the most updated version of DNS records, during the time the TTL (time-to-live) each has configured remains valid. Once the TTL expires, recursive servers naturally will look for the last update. In other words, they won’t look for the update exactly at the moment you made DNS changes, but when their TTL points zero seconds.