Every DNS record has a number attached to it called the TTL — time to live. It is measured in seconds, and it tells DNS resolvers around the world how long they are allowed to remember (cache) the record before they must ask again.
TTL is the reason DNS changes don’t appear everywhere instantly — and, used well, it is also how you make planned changes happen almost immediately.
How TTL Works
When someone visits your site, their resolver (usually their ISP or a public DNS service) looks up your record and stores the answer for the TTL. A record with a TTL of 3600 can be reused for up to one hour before the resolver checks back with your nameservers.
The catch: the TTL that matters during a change is the old one. If your record had a 24-hour TTL and you change it now, a resolver that cached it ten minutes ago may keep serving the old value for nearly another 24 hours. Lowering the TTL at the same moment as you change the record doesn’t help those resolvers — they never saw the new TTL.
Common TTL Values
| TTL (seconds) | Equals | Good for |
|---|---|---|
300 | 5 minutes | Short-term, just before and during a migration |
3600 | 1 hour | A sensible everyday default for most records |
14400 | 4 hours | Stable records you rarely change |
86400 | 24 hours | Very stable records such as NS; slowest to change |
The Lower-Before-You-Move Trick
For any planned change — moving hosting, switching email provider or changing nameservers — do it in three steps:
- At least one old-TTL period before the change (often 24–48 hours), lower the TTL on the records you will change to
300. - Make the change. Because resolvers now only cache for five minutes, the switch-over completes within minutes for almost everyone.
- Once everything is confirmed working, raise the TTL back to
3600or higher.
Confirm each stage with our DNS propagation checker — its “cache left” column shows the TTL each provider is still holding.
Why Not Keep TTL Low All the Time?
- More lookups: visitors’ resolvers have to ask your nameservers more often, adding a little latency to first visits.
- Less resilience: if your DNS provider has a brief outage, a longer TTL lets cached answers carry visitors through it.
- Some resolvers ignore very low TTLs and apply their own minimum anyway.
An hour is a good balance for most small business records.
What About Brand-New Records?
If someone looked up a name before it existed, their resolver may cache the “doesn’t exist” answer for a while (this is called negative caching, controlled by your zone’s SOA settings). That is why a newly added subdomain occasionally takes longer than expected to appear for a few people.
Nameserver Changes Have Their Own TTL
When you change nameservers, the record that matters lives at the domain registry, not with your DNS host — and registries commonly use TTLs of a day or more. You can’t lower that one, so nameserver changes usually take longest. More in how to change nameservers.
Frequently Asked Questions
Does TTL affect my website speed?
Only marginally, on a visitor’s first lookup. Page speed is driven far more by hosting, caching and page weight.
I changed a record and lowered the TTL — why is it still slow?
Resolvers that cached the record before your change are still honouring the old TTL. Wait it out, and lower TTL in advance next time. See DNS propagation explained.
Where do I change TTL?
In your DNS zone editor — for EDZNET hosting that’s the Zone Editor in cPanel, or just ask us and we’ll do it before your migration.
