Of all the free DNS sites that are available Xname ( http://www.xname.org ) stands out as probable the best around. This services caters for all sections of the DNS spectrum; IPv6, rdns and creation of subdomains as well as the standard DNS functions.
The service is free, but if you are using the service for multiple domains, it is suggested that you make a donation. By donating you are supporting the continuation of this Service as costs to maintain a venture of this magnitude is astronomical.
To conform to proper DNS standards Xname have invested in their own hardware and have two (2) nameservers totally committed to the project geographically dispersed. Therefore this Service is highly recommended to use for the registration and hosting of Domain Names from our service.