The tier-0 gateway is the entry point of the NSX-T Data Center network, and it is where the North-South service insertion takes place. The uplink of the tier-0 gateway is the point of connection between the NSX-T Data Center network and the external network.
The guest VM vNIC is the interface card inside the guest virtual machine, which is used to connect the guest VM to the NSX-T Data Center network. North-South services can be inserted at this point as well.

The two prerequisites before configuring the VMware Identity Manager (vIDM) service for NSX-T Data Center are Configure vIDM Integration and Certificate Thumbprint from vIDM. In order to use vIDM for authentication, it must be integrated with NSX-T Data Center, which will involve configuring the vIDM integration service. Additionally, a certificate thumbprint from vIDM must be provided to NSX-T Data Center to enable secure communication between the two services. Time synchronization and assigning roles to users are not necessary prerequisites for configuring the vIDM service. Reference: [1] https://docs.vmware.com/en/VMware-NSX-T/3.0/vmware-nsx-t-30-administration-guide/GUID-1B4EA3C9-8F43-4C4F-A86A-BFB0DB6D1A6C.html [2] https://docs.vmware.com/en/VMware-Identity-Manager/3.3/com.vmware.identity.install.doc/GUID-D56A0C0A-52F

When deploying an NSX Edge Virtual Machine through an ISO image, the virtual network interface card (vNIC) type that must be selected is VMXNET3 in order to allow participation in overlay and VLAN transport zones. VMXNET3 is a high-performance and feature-rich paravirtualized NIC that provides a significant performance boost over other vNIC types, as well as support for both overlay and VLAN transport zones.
For more information on deploying an NSX Edge Virtual Machine through an ISO image, please refer to the NSX-T Data Center documentation: https://docs.vmware.com/en/VMware-NSX-T-Data-Center/3.0/nsx-t-3.0-deploy-config/GUID-A782558B-A72B-4848-B6DB-7A8A9E71FFD6.html

In NSX-T, Identity firewall rules allow you to specify security controls based on the identity of the user, rather than the IP address or other network-based attributes. User identity can be used as a source in the firewall rule.