Using Nested Virtualization and specifically Nested ESXi, which is running ESXi inside of a VM, has become so automatic and second nature for me and many in the VMware community, that I sometimes forget we still have brand new users who are experiencing ESXi for the very first time.
Nested ESXi is an extremely powerful capability for so many different use cases from development, testing and general learning purposes. Before jumping in and deploying your Nested ESXi environment, which I highly recommend using my Nested ESXi Virtual Appliances, you need to make sure that you have proper networking setup or you will run into all sorts of strange issues. For all VMware Nested Virtualization resources, tips and tricks, you will definitely want to bookmark this page HERE.
Disclaimer: Nested Nested ESXi is not officially supported by VMware and Nested Virtualization is only supported under limited scenarios. For more details, please refer to this VMware KB 2009916.