fd6cdfac_ate__RA_API____Dyn_Help_Center__Description
[Field] hostname [Additional Info] Each hostname specified will be updated with the same information, and the return codes will be given one per line, in the same order as given. Example: hostname=test.dyndns.org,customtest.dyndns.org [Description] 
Comma separated list of hostnames that you wish to update (up to 20 hostnames per request). This is a required field.
Perform Update (RA-API) | Dyn Help Center
Description