Common questions about why DNS records take effect at different speeds after you add, modify, or delete them.
Why do newly added records take effect immediately?
They take effect immediately because no local DNS resolver has cached the record yet.
When a visitor queries a brand-new DNS record for the first time, their local DNS resolver has no cached answer. It performs a recursive query to the authoritative DNS server, gets the current record, and returns it to the visitor. There is no old cached value to wait for, so the record resolves instantly.
Note: This applies only to records added for the first time. If you delete a record and then re-add it, the old cached value may still exist on some resolvers, and the same propagation delay applies.
Why don't modified or deleted records take effect immediately?
Because local DNS resolvers cache the previous answer until its time to live (TTL) expires.
When you change or delete a DNS record, the authoritative DNS server is updated immediately. However, local DNS resolvers — deployed by ISPs (Internet service providers) or within corporate networks to accelerate DNS queries and reduce request load on upstream DNS servers — continue to serve the old cached answer until it expires. Only after the cache TTL runs out does the resolver fetch the current record from the authoritative server.
For example, if you update an A record to point to a new IP address, visitors whose local DNS resolver still holds the old IP will continue reaching the old address until that resolver's cache expires.
How long does it take for modified or deleted records to propagate?
In most cases, propagation completes within the TTL set on the record before the change.
The TTL is the primary factor. If your record's TTL was 10 minutes at the time of the change, all resolvers that respect the TTL will serve the updated record within 10 minutes. If the TTL was 3,600 seconds (1 hour), expect up to 1 hour.
Some ISPs override the TTL and cache records longer than specified. In the worst case, propagation can take up to 48 hours.
Recommendation: Before making a change that affects live traffic — such as switching an A record to a new IP address — make sure both the old and new IP addresses can serve requests normally. This prevents service disruption during the propagation window.
Why does a record update reach some regions faster than others?
Because each resolver independently caches the record, and they cached it at different times.
All resolvers honor the same TTL, but each started its cache timer at a different moment. Consider a TTL of 3,600 seconds: a resolver that cached the old record 55 minutes ago has only 5 minutes left before it fetches the updated record, while a resolver that cached it 2 minutes ago still has 58 minutes to wait. Same TTL, very different remaining wait times.
This is why visitors in one city may see your updated record almost immediately while visitors elsewhere still get the old answer for an hour or more. The difference comes down to when each resolver last refreshed its cache.
How long does it take for DNS server changes to take effect?
For details on how long DNS server changes take to propagate, see How long does it take for DNS server resolution to take effect? Why does it need 48 hours for resolution to take effect?