What is DNS TTL and what is the best value

What is DNS TTL and what is the best value
Remacle Jean-Claude
2 minutes
2022-01-28
what is
DNS

When you add or change a dns record, you will see the field "TTL".
In the most dns interfaces, this field will be filled in with a standard value, mostly 3600.

What is TTL

TTL (Time To Live) is the timing that the dns record will be held at the various DNS servers before it need to be refreshed.

The heigher the TTL is, the longer it will takes before the DNS change will become active and how lower the TTL is, the faster the dns record will be active.

In what is the TTL expressed

The TTL is a timing for the dns record, so in that case we expresse this value in seconds.

At the most DNS interfaces, the default value is 3600 seconds, so that is 1 hour.
The lowest TTL possible is 30 seconds.

What is best, a low or a high TTL value

We now know that the TTL is the timing before a DNS record becomes active and we know that the value is expressed in seconds.
So, what is the best value to give the DNS record?

Probably, you will say 30 seconds.
The lower the value, the faster you see the change and the better it is.

When to have a low TTL

  • when your DNS record updates the endpoint, like load balancing or failovers
  • best to use always a low TTL for all critical DNS record changes. Good range is between 30 and 150;

When to have a high TTL

  • records that point to the web server or to a CDN server
  • when you want made a change or add a new DNS record and you want to "plan" it in. For example, the website on the new server must come online within 24 hours.

Best practice

Every time you add or modify a TTL ask yourself the following.

“How long do I want the users to wait before they're going to see the changes?”

Conclusion

Setting a DNS record is sometimes not that easy, especially if you don't know what al those technical terms mean and how they work.

jCreativeWeb can help you by setting the correct DNS records.

Contact us