The vSphere HA and DRS troubleshooting topics provide solutions to potential problems that you might encounter when using those specific vSphere cluster functions.
Note that vSphere FT is related to vSphere HA and, generally, it's related to the availability topic, but it's a function at VM level.
Objective 7.5 for VCP65-DCV and VCP6-DCV are the same since there weren't big changes in the troubleshooting approach from vSphere 6.0 to vSphere 6.5.
The vSphere 6.5 Troubleshooting guide contains in-depth information and examples on this topic: https://docs.vmware.com/en/VMware-vSphere/6.5/vsphere-esxi-vcenter-server-651-troubleshooting-guide.pdf.