NSX requires an MTU of 1600 to allow for VXLAN encapsulation… I think this point on the exam blueprint is basically alluding to the dVS being setup to transfer a minimum of 1600 MTU (although when I setup a dVS I tend to set them to 9000 in case we use vSAN or iSCSI over the switch.
1 – Open the web client and browse to the dVS that will be used for VXLAN
2 – Select manage then Properties then Edit then Advanced:
3 – Change the MTU (Bytes) field to a minimum of 1600 and click ok