Full or Half Duplex

1. Find out if your NIC is full duplex capable.

2. Check for an indicator light on the back of the NIC.

3. Look at the device manager settings.

4. Run diagnostic software from the manufacturer.

5. Attach to a hub that indicates whether or not the card is communicating in full duplex.

1. Check the driver properties, now a days most of the card provide utilities to check the mode.

2. Ethernet physical connectors provide circuits including the receive (RX), transmit (TX), and collision detection. When half duplex Ethernet is implemented, the TX circuit is always active at the transmitting station. When another station is transmitting, the station's RX circuit is always active. Full duplex Ethernet Switching provides a transmit-circuit connection wired directly to the receiver circuit at the other end of the connection.

Hope this helps.
Good luck