TTL, short for Time To Live, is a value attached to every DNS record that tells other servers how long they may cache that record before checking again. It is measured in seconds, and while it sounds technical, understanding TTL helps you make DNS changes smoothly and predict how long they take to appear. This guide explains what TTL does and how to set it sensibly.
What TTL actually controls #
When a server looks up one of your DNS records, it stores the answer for the length of the TTL so it does not have to ask again every time. A longer TTL means the record is cached for longer, which reduces lookups but makes changes slower to take effect. A shorter TTL means changes propagate faster but results in more frequent lookups. In short, TTL is a trade-off between stability and flexibility.
Common TTL values #
- 3600 seconds (1 hour): a sensible default for most records.
- 86400 seconds (24 hours): good for records that rarely change, reducing lookups.
- 300 seconds (5 minutes): useful temporarily when you are about to make changes.
How to use TTL when making changes #
If you know you are going to change a record soon, such as moving your site to a new server, it helps to lower the TTL in advance. The recommended approach is:
- A day or two before the change, lower the TTL on the relevant record (for example, to 300 seconds).
- Wait for the old, longer TTL to expire so the shorter value takes effect.
- Make your change; it will now propagate quickly.
- Once everything is confirmed working, raise the TTL back to a normal value.
This minimises the window where visitors might see the old settings.
How to set TTL #
- Log in to your DNS manager or control panel.
- Open the DNS or Zone Editor section.
- Edit the record you want to change.
- Set the TTL field to your chosen value in seconds.
- Save.
Troubleshooting #
- Change taking too long: the old TTL may still be cached; wait for it to expire.
- Too many lookups: raise the TTL on stable records.
- Planning a migration: lower the TTL well before you switch.
Need help? #
If you are preparing a DNS change and want to time it well, our support team can advise on the right TTL over live chat.
