Why DNS Changes Can Take Seconds for Some Users and Hours for Others

When a DNS record is updated, the change does not instantly reach all users because DNS operates on a cache-expiry model, not a push-notification system. Each resolver — such as Google Public DNS, Cloudflare, or an ISP like Deutsche Telekom — independently caches records and only fetches a fresh copy once its cached version expires. Propagation time is therefore shaped by a record's TTL setting combined with each resolver's own minimum TTL policies, which vary widely: Google honors TTLs closely while Deutsche Telekom enforces a minimum of 3,600 seconds across a three-tier cache hierarchy. Geographic distribution adds further complexity, as Cloudflare's 330-plus edge locations may expire caches at slightly different times across cities. This means two users can simultaneously receive contradictory results — one seeing the updated record within minutes and another waiting up to 24 hours — and both experiences are technically accurate from their respective resolver's standpoint.