DNSpropagation

DNS propagation refers to the time required for changes to DNS records to become visible across the internet after updating authoritative DNS servers. It occurs because many resolvers and caches store DNS responses to speed up lookups.

When you update a zone, the new data becomes authoritative, but recursive resolvers may continue to serve cached records until their TTL expires. Each DNS record has a TTL (time to live) that tells caches how long to keep the data. After TTL expires, queries fetch the new information from authoritative servers. Changes can involve A, AAAA, CNAME, NS, or other record types, and may also affect glue records for child zones.

Propagation is influenced by TTL settings, the distribution and update frequency of resolvers, network topology, and any intermediaries such as content delivery networks. Changes that touch glue or NS records can complicate resolution in some environments. In some configurations, DNSSEC or misconfigurations can also affect visibility or validation of records.

Practical guidance: to minimize downtime when changing essential records, reduce the TTL on the affected records to a small value well before the change, perform the update, and then gradually restore the TTL. Verify propagation by querying from multiple locations with tools like dig or nslookup, or use online DNS propagation checkers. Because propagation depends on many independent caches, full visibility can take from minutes to up to 48 hours or longer in edge cases. See also DNS caching and TTL for related concepts.