I've just had a practice test for the N10-004 and passed with flying colours. Taking my real exam on Tuesday and can't wait!

There was however one of the questions that I would like to query as I think the answer may have been incorrect.

The question was:
"You are using Gigabit Ethernet as the backbone of your LAN. What is the access method for Gigabit Ethernet?

The answer was CSMA/CD which I answered correctly because it was definitely not any of the other choices.

But it got me thinking... The Professor mentioned in one of his videos that there was never any standard implemented for half duplex on Gigabit Ethernet as everything would be running at full duplex, and doesn't CSMA/CD only apply for half duplex Ethernet?

I'm not 100% on this - maybe someone else can clarify.

I thought CSMA/CD only applied to nodes communicating on a network and didn't apply to duplexing at all. Full duplex simply means a network media is capable of sending and receiving at the same time whereas CSMA is where a node is listening to see if the line is free to transmit.

Therefore I think it would work both ways, if a line was full duplex, the incoming signals would be listening to transmit and the outgoing signals would be doing the same.

Gigabit Ethernet does include as part of the specification a method for half-duplex, but no manufacturer has ever created a Gigabit Ethernet hub.

When in half-duplex mode, Gigabit Ethernet's access method is CSMA/CD (carrier sense multiple access with collision detection). Full-duplex connections don't need or use CSMA/CD, since there's nobody else on the network to worry about colliding with.