A computing resource service receives a request from a customer to assign a domain name to a computing resource. The computing resource service may submit a query to a domain name system service to determine whether the domain name has been reserved for the customer. The domain name system service may provide an encrypted alias record corresponding to the requested domain name and specifying one or more identifiers of customers for whom the domain name has been reserved. The computing resource service may decrypt the alias record and determine whether the customer corresponds to one of the one or more identifiers within the alias record. If the customer does correspond to one of the one or more identifiers within the alias record, the computing resource service may assign the domain name to the computing resource.