I would have to ask why the need to have RHEL 6.x and 7.x on the same cluster. It sounds to me that dual running of different RHEL versions can be readily avoided. The recommendation would be to have one OS version.
This scenario might be supported in the future, but as you are on 2.4.2, would advise one RHEL version per HDP cluster.
Hi @Oleg Ruchovets Please don't mix OS versions on a single cluster, it'll very likely get you into some serious issues down the line, it also wouldn't be a supported scenario from a Hortonworks Support perspective if that's important to you unless it happened as part of a rolling OS upgrade across a single cluster.