Ethernet interview questions

1. What is Ethernet –

Ethernet is a medium which is used by devices like computers, switches, routers, hubs etc. If two devices wishes to send data among each other using ethernet technology, both the devices should support ethernet. For example, there are network interface cards which support ethernet, switches and routers which support ethernet network cards. Ethernet comes at the layer 2 of the OSI Model and Layer 1 of the TCP/IP Model.

2. What is an ethernet frame -

An ethernet frame is used for encapsulating data from the higher layers of the TCP/IP Model. Assume that a PC1 pings PC2. The ping , which is an ICMP packet along with the IP Header is encapsulated in the ethernet frame. The frame is used for carrying the ping packet and ultimately deliver it to PC2.

3. What are the components of an ethernet frame?

Ethernet frames are of different types. Typically they consist of the source mac-address, destination mac-address, data from the upper layer, type of data like IP, IPX etc, preamble (for clocking) and a FCS value for identifying the validity of the frame (Checks if the frame is invalid, corrupt, etc)

4. How is an ethernet frame constructed?

An ethernet frame is constructed by the network card. When data on the operating system , comes down to the network card, the frame would be constructed to send the data out on the network.

5. How is a frame received at the destination?

The preamble field is looked into first inside a frame. This is purely for synchronization. This is followed by the destination looking into whether the frame is intended for itself or not, by checking the destination mac-address. Once the mac-address is verified, the FCS value is calculated. If a mismatch is found, the frame is discarded. Else, the data type of the frame is looked into and the data is send to the appropriate layers of the operating system

(IP Layer).