iPadOS 9.1 (build 13B143) is an official Apple over-the-air update for the iPad 2 (WiFi), released on 2015-10-21T17:15:48Z. The update package is 111.52 MB. This is a delta (partial) update that requires 9.0 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: d9f645cf16de87427caf8ddb3a873ecef4379df1.zip.