🕓Utilities

Recommended DNS TTL

Suggests a DNS TTL for five situations - stable record, migration, dynamic load balancer, failover and CDN - ranging from 86400s down to 30s, with the reason why.

Scenario

Suggested TTL

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Choosing the TTL for a DNS record

TTL is the number of seconds a resolver may hold on to an answer before asking again. It is a trade between two things that pull in opposite directions: a high TTL cuts queries, speeds up browsing and shields the domain if the authoritative server goes down; a low TTL makes any change spread quickly, at the cost of more query traffic.

Pick the scenario and the page shows the range used in practice, with the reasoning. A stable record that has not changed in months is happy at 24 hours. A record mid-migration wants 300 seconds, so a mistake can be reverted in minutes. A load balancer that changes addresses often works around 60 seconds, and failover configuration goes lower still, near 30.

The costliest mistake is not picking the wrong number, it is picking at the wrong time. Lowering the TTL on migration day means discovering that the reduction only takes effect once the old TTL expires in every cache — if it was 24 hours, that is a full day of waiting. The correct procedure is to lower the TTL at least one old TTL in advance, make the change, verify, and only then restore the higher value.

Frequently asked questions

Why has my DNS change not propagated yet?

Propagation is the popular name for "the caches have not expired yet". Each resolver holds the answer for the TTL it received, and every one of those clocks started at a different moment. Check with dig +noall +answer yourdomain, which shows the remaining TTL at that particular resolver.

What is the lowest TTL worth using?

Below 30 seconds the benefit fades, because many resolvers enforce a floor of their own and ignore very low values, while query cost climbs. For real failover a low TTL helps but does not replace health checks with route switching — plenty of clients hold an address past its TTL.

Is the SOA TTL the same as the record TTL?

No. SOA carries its own timers, and its last field, minimum, defines how long a negative answer may be cached — how long a "this name does not exist" stays in force. That is why a newly created record can be slow to appear if someone queried the name before it existed.

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