Troubleshooting storage and networking is usually more complex because they can be interconnected (for example, for IP-based storage) or the issue or the root cause could be completely outside the vSphere perimeter, such as in the storage fabric or in the network switches.
Objective 7.2 for VCP65-DCV and VCP6-DCV are the same, just because 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: https://docs.vmware.com/en/VMware-vSphere/6.5/vsphere-esxi-vcenter-server-651-troubleshooting-guide.pdf.