Mesos-DNS is officially under development by the team at Mesosphere. Since mesosphere stoped to support DC/OS, AVENTER UG (haftungsbeschraenkt) forked Mesos-DNS to ensure the future development. The team keeps an eye on issues and questions in a few places.
You can report issues and bugs at the Mesos-DNS Github repository.
You can get advice on Mesos and Mesos-related projects from the Apache Mesos IRC channel and mailing lists.