The Enable User Data setting allows you to pass arbitrary data into the user-data key of the DigitalOcean Metadata service. It is available in regions that are running v1.5 of our backend. You may run this command on a droplet, to retrieve the user-data that you supplied at its creation time:
curl -w "\n" http://169.254.169.254/metadata/v1/user-data
Currently, the Enable User Data setting is only required for the clustering of CoreOS droplets. For more information about using the setting with CoreOS, read this tutorial: How To Set Up a CoreOS Cluster on DigitalOcean
We are expanding this feature and will be providing much more documentation around it soon. Besides CoreOS it will be useful for providing scripts and initial configuration information to your droplet on CentOS 7 and Ubuntu 14.04.
Private networking allows your droplet to communicate with other droplets in the same datacenter without being exposed to the larger internet. One common use case is when you have your front-end application and database on separate servers in order to lock down access to the database server. For more info, check out: