iPadOS 9.9.11.2.1 (build 15C153) is an official Apple over-the-air update for the iPad Pro 12.9-inch (Cellular), released on 2017-12-13T18:09:56Z. The update package is 1.28 GB. This is a delta (partial) update that requires 9.3.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 74b540abac126e5e48a04aed601f65446b60d2d0.zip.