Antelope supports two main branches of Linux, RedHat Enterprise Linux (RHEL) and CentOS Linux.
Specifically for Antelope 5.6:
We can make no promises nor offer support for Antelope 5.6 on other versions of Linux.
Note that on the 7.x versions of RHEL and CentOS Linux we are only able to offer IP-based licenses (no node licenses based on the serial number of the machine) due to technical limitations of these versions of Linux. For version 6.7 of RHEL/CentOS, we are still able to offer node (serial-number-based) licenses as well as IP-based licenses.
We arrived at support for these two Linux variants after a survey of our Enterprise customers. Their overwhelming consensus at the time was to pick RedHat.
While we understand there are many extant versions of Linux available which may be of interest, in practice there are far too many for us to support. Witness the number of valid variants shown by the Linux Distribution Timeline on Wikipedia. In order to support any of these releases we need to run a copy in-house, then pay staff to investigate and resolve any problems that arise on each particular version. In practice we cannot properly support more than a couple versions of Linux without substantially increasing the cost of our software. We regret any inconvenience this may cause.
We often hear arguments that one or another version of Linux (Fedora, Scientific Linux, etc.) is almost or essentially the same as one of our supported versions, and that Antelope should therefore work on the named variant. While this may be true to zeroth order, for operations-grade software such as Antelope, the few small differences amongst nominally similar Linux versions are sometimes enough to create performance problems that degrade the application below our quality standards. These problems, when they occur, are frequently insidious and extremely resource-intensive to find and fix. We are thus back to the point made above, that we cannot afford to support more than a couple versions of Linux. We are forced to interpret that version support in the strictest sense.