DNS propagation is the delay between changing a DNS record and that change being visible everywhere on the internet — caused by caching at every layer between the authoritative nameserver and the end user.
What determines the delay
- The record’s TTL (time-to-live) value — a 24-hour TTL means some resolvers may cache the old value for up to 24 hours after the change
- ISP and local resolver caching behavior, which can sometimes ignore TTL and cache longer
- Your own device/browser DNS cache
Practical guidance
Lower the TTL to a short value (e.g. 5 minutes) a day or two before a planned DNS change, so the old, longer TTL has already expired everywhere by the time you make the actual change — this is the standard way experienced teams minimize propagation delay for planned cutovers.
FAQ
Why does a DNS change show up for me but not for other people?
You’re likely seeing your own device or local resolver’s fresh (uncached) lookup, while others are still being served a cached value from before the change.