What is Propagation Delay?
Propagation delay is the time it takes for DNS changes, such as updated nameservers or modified DNS records, to spread across all DNS servers worldwide and become fully effective.
How Does Propagation Delay Work?
When you make a change to your domain's DNS records, the update starts at your authoritative DNS server but must propagate to recursive DNS resolvers around the globe. These resolvers cache DNS records based on the TTL (Time to Live) value, meaning they will continue serving the old record until the cached version expires. This is why DNS changes are not instant and can take anywhere from a few minutes to 48 hours to fully propagate.
During the propagation period, different users in different locations may see different versions of your DNS records depending on which cached version their local resolver holds. This can result in some visitors reaching the old server while others are directed to the new one. To minimize propagation issues, it is common practice to lower the TTL value well in advance of planned DNS changes, reducing the time resolvers hold onto stale records.