High Quality Content by WIKIPEDIA articles! A network monitoring interface card or NMIC is similar to a network card (NIC). However, unlike a standard network card, an NMIC is designed to passively (and silently) listen on a network. At a functional level, an NMIC may differ from a NIC, in that the NMIC may not have a MAC Address, may lack the ability to transmit and may not announce its presence on a network. Advanced Network Monitoring Interface Cards have features that include an ability to offload CPU intensive processing from a system`s CPU, accurate time measurement, traffic filtering, and an ability to perform other application specific processing.