@ priyanka manwani to reach message of 1 byte of application layer to data link layer ,it will come through transport layer then network then it will reach at data link layer.since every layer add its own header to message ,so 1 byte(application layer data)+20(tcp header)+20(ip header)=41 byte of packet will reach at data link layer and it will be payload for frame but we know payload of frame should be greater than 46 and less than 1500 byte.but we are getting 41 byte so we have to add padding byte to it (41+5=46 byte) .so ethernet frame size will be 46+26=72 Byte.