DNS Propagation

It runs the same query against several public resolvers (Google, Cloudflare, Quad9 and a default resolver) at once so you can see whether a DNS change has reached all of them yet.

Usually minutes to a few hours, bounded by the record's TTL. A record with a 3600-second TTL can be cached for up to an hour after you change it.

Large sites often return several rotating IP addresses for load balancing, so resolvers legitimately hand back different subsets. That is normal, not a propagation problem.