During its initialization, the manager attempts to pull the newest datafile from the CDN servers. After this, the Optimizely manager can periodically check for and pull a new datafile at the time interval you set during its initialization. The process of checking for and downloading a new datafile is called _datafile polling_.

By default, the manager only checks for a new datafile during initialization. **To enable periodic datafile polling, you must define a polling interval when building the manager**. This value is the number of seconds the manager waits between datafile polling attempts.

## Usage notes

• In Android, the minimum polling interval is 60 seconds. In iOS, the minimum polling interval is 2 minutes while the app is open. If you specify shorter polling intervals than these minimums, the SDK will automatically reset the intervals to 60 seconds (Android) or 2 minutes (iOS).

• Updated datafiles do not take effect until your app is restarted or when you re-initialize the Optimizely manager. This implementation strategy allows the data to change while the app is running without causing nondeterministic behavior.

• The Optimizely manager only checks for new datafiles when the SDK is active and the app is running. Datafile polling is never done while the app is in the background.

## Android

To override the default datafile handler and use your own, implement [DatafileHandler](🔗).