When your customer opens your app for the first time after installing or updating it, the manager attempts to pull the newest datafile from Optimizely's CDN. If your app is unable to contact the servers, the manager can substitute a datafile that you included (_bundled_) when you created your app.
By bundling a datafile within your app, you ensure that the Optimizely manager can initialize without waiting for a response from the CDN. This lets you prevent poor network connectivity from causing your app to hang or crash while it loads.
Datafile bundling works with both synchronous and asynchronous initialization because reverting to a bundled datafile happens during the Optimizely manager's initialization, before a client is instantiated.