You can set an IP address on a user that will be used as the effective IP whenever that user makes an request. For example, the actual IP address of the user may be proxied or unreadable at serving time, which would require you to use a stored IP.

An HTTP status of 200 indicates that the IP address was set on the user. If you read the user's key using the /read endpoint, you'll see the new top-level parameter ip with the IP address.