So for the monitoring of ESXi Host level and vCenter level I can only do it via the ActiveGate-way is it?
Can't I do it using OneAgent-way? (i.e installing OneAgent in them.)
For my case, I only want to monitor further down in the ESXi Host level, I don't need to monitor vCenter.
So....would installing OneAgent in the ESXi Host work?
Only via Activegate as the module is part of ActiveGate. It's not a matter if you are using ESX or Center. The vmware integration in Dynatrace is using the code that is only part of the ActiveGate.
With Dynatrace Managed you can use the embedded ActiveGate on the Cluster node - no reason to install an ActiveGate if you have connection to the ESX/vCenter from the Dynatrace Cluster nodes. With SaaS you must install an ActiveGate.
Oneagent on ESX would not help and I don't think this is even possible nor supported.