Request Frequency

Update requests

To prevent server overload and to benefit from optimal protection, the Update API imposes time intervals for how often a client can send requests to the Web Risk server to perform URL checks ( or to update the local database (threatLists.computeDiff).

The initial request for data must happen at a random interval between 0 and 1 minutes after the client starts or wakes up. Subsequent requests can happen only after the minimum wait duration or back-off mode time limit has been observed.

Minimum wait duration

Both the response and threatLists.computeDiff response have a minimumWaitDuration field that clients must obey.

If the minimumWaitDuration field is not set in the response, clients can update as frequently as they want and send as many threatListUpdates or fullHashes requests as they want.

If the minimumWaitDuration field is set in the response, clients cannot update more frequently than the length of the wait duration. For example, if a fullHashes response contains a minimum wait duration of 1 hour, the client must not send send any fullHashes requests until that hour passes, even if the user is visiting a URL whose hash prefix matches the local database. (Note that clients can update less frequently than the minimum wait duration but this may negatively affect protection.)

Back-off mode

For the recommended backoff procedure, read our Service Level Agreement.