What is DNS TTL

Every DNS record has a TTL, which instructs the OS to cache the DNS record for that period of time (in seconds) and not contact the DNS server for at least that long. This is used to reduce the amount of DNS queries clients make, and can have positive performance implications.

This Profile Option allows you to override the TTLs to whatever values you wish. This feature can sometimes be called "Cache Boost", if you increase the TTLs to non-default values. By doing so, you instruct your OS to cache DNS records for longer periods of time.

Each field is an override measured in seconds. Enable the option, enter the value you want, and allow it to save. Turn the option off to restore normal behavior. The starting values are 10 seconds for Block TTL, 20 seconds for Redirect TTL, and 60 seconds for Bypass TTL. With Bypass TTL off, responses use their upstream TTLs, not a fixed 60-second value.

Changing a TTL does not clear answers that a device has already cached. Applications may also maintain their own caches.

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Know what you're doing

Don't change these randomly, or set them too high as this can have adverse consequences with CDNs. By high we mean "measured in days".

There are 3 TTLs that you can tweak in Profile Options.

Block TTL

See the dedicated Block TTL guide for setup and trade-offs.

This overrides the TTL for DNS records that were blocked by Control D. The default block TTL is 10s. Increasing this value will result in fewer DNS lookups (for things that are blocked), but will also increase the time between you unblocking the domain and it actually becoming unblocked.

Redirect TTL

See the dedicated Redirect TTL guide for setup and trade-offs.

This overrides the default TTLs on DNS responses that were redirected by a Service, Custom Rule or Default Rule. The default redirect TTL is 20s. Increasing this value will result in fewer DNS lookups, but will also increase the time between you changing locations and your new location settings being actually enforced on a Device.

Bypass TTL

See the dedicated Bypass TTL guide for setup and trade-offs.

This overrides the TTL for all DNS records that were bypassed (not subject to any BLOCK or REDIRECT rule) and sent to the upstream resolver. Increasing this value will result in fewer DNS lookups, but can break websites if you set this too high. Values above 1 day are not recommended.