What TTL Means
TTL (Time To Live) is a number of seconds attached to every DNS record. It tells resolvers how long they may cache the answer before asking again. A record with TTL 3600 can be served from cache for up to one hour.
You can see the TTL of any record with our DNS Record Lookup. When a resolver shows a TTL lower than the value you set, it is the time remaining in its cache.
Why TTL Matters
- Change speed: after you edit a record, resolvers may serve the old value until its TTL expires. That is most of what people call “propagation” — see how to check DNS propagation.
- Performance: longer TTLs mean more answers come from cache, so lookups are faster for visitors.
- Load and resilience: long TTLs reduce queries to your nameservers and keep a domain resolvable from caches during a short nameserver outage.
Practical Values
| Situation | Typical TTL |
|---|---|
| Stable website and mail records | 3600 (1 hour) to 86400 (1 day) |
| Records you change occasionally | 3600 |
| Before a planned migration | 300 (5 minutes) |
| Failover or load-balancing setups | 30 to 300 |
| NS records | Often 86400 or more |
Many DNS providers use 300 or 3600 as a default, which works for most sites.
How to Use TTL for a Smooth Migration
- At least one old-TTL period before the change, lower the TTL to 300.
- Wait until the old TTL has passed, so caches hold the short TTL.
- Change the record. Resolvers pick up the new value within minutes.
- After everything is confirmed, raise the TTL back to a longer value.
Lowering the TTL at the same moment as the change does not help: caches that already have the record keep the old TTL.
Things TTL Does Not Control
- Nameserver changes at the registry: the TTL of the delegation is set by the top-level domain, not by you.
- “Does not exist” answers: negative caching is controlled by the SOA record — see why DNS changes are not showing.
- Some resolvers and applications enforce their own minimum or maximum cache times.
Very Low TTLs: Downsides
TTLs of a few seconds increase query volume and make every visitor wait for fresh lookups more often. Use them only where fast failover really matters.