cnames.dev / tools / dns propagation checker
DNS Propagation Checker
Check A, AAAA, CNAME, TXT and MX records across public resolvers to see if a change has taken effect.
What DNS propagation actually is
"Propagation" is a slight misnomer — DNS doesn't push changes outward. Instead, resolvers cache records for the duration of their TTL. When you change a record, resolvers keep serving the old value until their cached copy expires, then fetch the new one. So propagation time is really cache-expiry time, governed by the TTL that was in effect before your change.
Reading the results
This tool queries Cloudflare and Google's public resolvers and compares their answers for the record type you pick. If both agree, the change has landed on those resolvers. If they differ, you're watching propagation in progress — one resolver still holds the old cached value.
Speeding up a planned change
- Lower the TTL (to ~300s) a day or two ahead. Wait for the low TTL to itself propagate.
- Make the change; it now expires from caches within ~5 minutes.
- Raise the TTL back up once you've confirmed the new value everywhere.
Custom domains and propagation
When a customer points their domain at your SaaS, the certificate can only be issued once DNS resolves to your platform. If issuance seems stuck, this checker confirms whether the customer's record has actually propagated yet. On cnames.dev, verification and issuance are automatic once the record is live.
Building a SaaS that needs custom domains? cnames.dev automates DNS, SSL, and edge routing — one API call per domain, free for 25 domains. Start free or read the docs.
Frequently asked questions
How long does DNS propagation take?
Usually minutes to a couple of hours, bounded by the record's TTL and resolver caches. If the previous record had a long TTL (e.g. 24h), resolvers can keep serving the old value until it expires.
What does "propagated" mean here?
We query multiple public resolvers and compare their answers. When every resolver returns the same set of values, the change has propagated to those resolvers.
How can I make changes propagate faster?
Lower the record's TTL (e.g. to 300 seconds) a day or two before the change. Once the low TTL is itself propagated, the actual change will be picked up within that TTL.
Which record types can I check?
A, AAAA, CNAME, TXT and MX — covering website routing, custom domains, and email configuration.