POST /

Content-Type: application/x-www-form-urlencoded

Action=AssignPrivateNatGatewayAddress&DryRun=true&NatGatewayId=__NatGatewayId__&PrivateIpAddress.1=__Member__&PrivateIpAddress.2=__Member__&PrivateIpAddressCount=1&Version=2016-11-15