OSI layer for promiscous / monitor mode On what OSI layer do network cards operate when the use 1. promiscuous mode 2. monitor mode ?

A NIC covers layers 1 and 2.

Promiscuous mode is when the NIC ignores the destination MAC address which is part of layer 2. Normally, a NIC ignores all frames with a destination MAC other than their own or the broadcast address.

Monitor mode only exists for wireless NICs - when they receive independent of their (logical) link status all the time - more or less a layer 1 thing.