A few days after announcing the rollout of the Android 5.1.1 update for the Nexus 9, Google has uploaded the factory image for the tablet on its website.
Right now, the Android 5.1.1 (LMY47XZ) factory image is only available for the Wi-Fi variant of the Nexus 9. Looking at how long it usually takes Google to upload factory images of its 3G enabled Nexus tablets, I’d guess the Android 5.1 factory image for the LTE Nexus 9 is, at best, still a few weeks away.
In addition to the factory image, the download link of the Android 5.1.1 OTA update for the tablet has been captured as well. The 401MB OTA update is only for Wi-Fi variants of the Nexus 9 that are running Android 5.0.2 (build LRX22L). If you have not received the OTA update, you can download it from below and manually sideload it on your tablet right away.