What Is TTL?

TTL (time to live) specifies how long records are cached on a local DNS server.

The local DNS server is connected to clients (computers or smartphones) through the Internet. By default, its address is assigned by the broadband carrier. You can also choose a public DNS server, for example, 114.114.114.114 or 8.8.8.8, as your local DNS server.

When receiving requests for a domain name, the local DNS server asks the authoritative DNS server for the required DNS record, and then caches the record for a period of time. During this period, if the local DNS server receives requests for this domain name again, it will not request the record from the authoritative DNS server, but directly returns the cached record.

The time records are cached on the local DNS server is specified by the TTL value. You can set it when adding record sets in public or private zones. For details, see Managing Record Sets.

The effective time of the following operations depends on the TTL value (to accelerate the process, decrease the TTL value):

• Adding a record set
• Modifying or deleting a record set
• Changing DNS server addresses