DNS Propagation Checker

"Propagation" is the most misleading word in DNS. Nothing is pushed from your registrar to servers around the world when you change a record. What actually happens is simpler — and entirely under your control.

Every DNS record you publish carries a TTL (time to live): the number of seconds a resolver is allowed to keep serving its cached copy before it must ask your nameservers again. When you switch your site to a new server, resolvers that looked your domain up a minute ago keep answering with the old address until that timer runs out. A resolver that has never seen your domain — or whose cache just expired — returns the new one immediately. That mix of fresh and stale caches, expiring on independent schedules all over the world, is the entire phenomenon people call propagation. It is cache expiry, not distribution.

That is why this checker asks 21 resolvers at once. Green dots have picked up your change; amber dots are still serving a different (usually older) answer; and the split between them tells you roughly how far along you are. Disagreement mid-change is normal and healthy. If the map still disagrees long after your old TTL has elapsed, something else is wrong — a stale secondary nameserver, a proxy cache, or a record you forgot to update.

The practical lesson: lower your TTL before you migrate, not after. A day or two ahead of a planned change, drop the record's TTL from the typical 3600–86400 seconds to 300. Wait for the old, long TTL to expire everywhere (that takes as long as the old TTL — this is the step people skip), then make the switch. Caches worldwide now converge within five minutes instead of a day, and you can raise the TTL back once the map is solid green. Keep in mind that a few ISP resolvers ignore very low TTLs and cache longer than you asked — another reason to check from many vantage points instead of just your own machine, where your OS and browser add caches of their own.

DNS is also a single point of failure that most teams never watch: an expired domain, a hijacked nameserver or a fat-fingered record can take you offline while your web servers hum along happily. If your DNS setup matters to you, read our guide to choosing a DNS provider and building in redundancy, see how CompleteStatus DNS monitors snapshot your records and alert on unexpected changes, or start monitoring your DNS continuously, free — so the next change you see on this map is one you made yourself.