Google, which recently rolled out the developer preview version for its new Android operating system dubbed Android N, has now begun seeding first preview builds for compatible Nexus devices such as Nexus 5X, 6P, 9 and 9G.
The over-the-air update brings a new build version NPC56W for Nexus 5X and 6P. The Nexus 9 or 9G should receive build version NPC56X. This OTA is not available for other devices such as Nexus 6, Nexus Player, Pixel or General Mobile 4G (Android One).
If you have access to a supported Nexus device, you would be able to receive the OTA update for the new preview version of Android N by enrolling the device in the Android Beta Programme. The preview updates are automatically downloaded and will update your device like any other software update.
Alternatively, you might consider installing factory images for the latest preview build. It is important to note that manually flashing a device is useful in case you wish to have precise control over the test builds or need to reinstall the updates. But installing system images on a device would wipe out all data of the device. Therefore, it is recommended that you create a backup of all important data before you go ahead with the manual flashing. Also, keep in mind that manually flashed system images do not automatically push OTA updates to the later Developer Preview builds.