iPadOS 11.2.1 (build 15C153) is an official Apple over-the-air update for the iPad Air (Cellular), released on 2017-12-13T18:04:09Z. The update package is 1.01 GB. This is a delta (partial) update that requires 10.3.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: c678be79c3e24cb7f31ed3b9c8763ba8d4d3df25.zip.