What is DNS propagation?
Learn what DNS propagation means, why different resolvers may show different answers, and what to check during a DNS change.
What people mean by DNS propagation
DNS propagation is the period after a DNS change when different resolvers may still return different answers.
In practice, this is usually about caching and TTL behaviour rather than a magical global update process happening all at once.
Why answers differ
Resolvers cache DNS answers. If one resolver cached the old answer and another has already fetched the new one, you may see different results during the change window.
This is why checking more than one resolver is useful.
What to look at
- The exact record type you changed
- Whether different public resolvers return different answers
- Whether TTL values explain the timing
- Whether the authoritative answer is what you expect
Common misunderstanding
People often say DNS propagation as if every system updates simultaneously after a set number of hours. In reality, different resolvers may refresh at different times depending on their cache state and TTL handling.
That means propagation is best understood as a cache visibility issue.