DNS propagation is the process by which DNS record updates spread across the global network of DNS servers. When you change a DNS record, that change doesn't happen instantly everywhere—it takes time for DNS caches worldwide to expire and fetch the new records.
How DNS Propagation Works
When you update a DNS record at your registrar or DNS provider, the change is made on your authoritative nameservers. However, DNS resolvers around the world have cached copies of your old records. These caches won't refresh until the TTL (Time To Live) expires. Only then will they query the authoritative servers for the new records. This is why propagation takes time—you're waiting for caches to expire globally.
Why Propagation Times Vary
Propagation time depends on several factors: the TTL value set on your records (higher TTL = longer propagation), whether ISPs respect TTL values (some cache longer), geographic distance from authoritative servers, and the specific DNS resolver being used. Corporate networks and ISPs may have their own caching policies that differ from the TTL you set.
The 24-48 Hour Myth
You'll often hear that DNS propagation takes 24-48 hours. This is based on the maximum TTL values commonly used. In practice, if your TTL is set to 300 seconds (5 minutes), most resolvers will have the new records within 5-10 minutes. The key is planning ahead and lowering TTL before making changes.
Checking Propagation Status
To verify propagation, you need to query DNS servers in different geographic locations. Our API does this automatically, checking from multiple continents and reporting which locations have received the update. This gives you confidence before decommissioning old infrastructure or announcing a migration complete.