DNS Propagation Validation

When you change a DNS record, resolvers around the world don't update instantly — each one serves its cached copy until the TTL expires, then re-queries the authoritative nameserver. Propagation is the time it takes for all resolvers globally to start returning the new value.

It depends on the record's TTL. A TTL of 3600 means resolvers may cache the old value for up to one hour. In practice most resolvers update within minutes after the TTL expires, and the majority of global traffic sees the new record within 1–24 hours. Pre-lowering your TTL to 300 seconds a day before a planned change dramatically speeds this up.

Different IPs from different resolvers is normal for CDN and anycast setups — providers like Cloudflare, Akamai, and AWS Route 53 intentionally return different addresses based on the resolver's geographic location to route users to the nearest edge node. If you're NOT using a CDN and see different IPs, it may indicate incomplete propagation or a misconfiguration.

Those resolvers cached the record before you made the change and their cached copy hasn't expired yet. Wait for the old TTL to pass — the resolver will re-query the authoritative nameserver and get the new value. You can also try flushing the public resolver's cache (Google and Cloudflare offer cache flush tools on their websites).

Split-horizon (also called split-brain DNS) returns different records depending on where the query comes from — typically internal corporate resolvers get private IPs while public resolvers get public IPs. This lets internal users reach internal services while external users reach the public-facing endpoint.