iPadOS 11.2.1 (build 15C153) is an official Apple over-the-air update for the iPad Air (WiFi), released on 2017-12-13T18:03:44Z. The update package is 327.28 MB. This is a delta (partial) update that requires 11.1.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: b312c71d753ca2cd613cdef4f9b1fc2c426262ef.zip.