fix computer errors

Network layer – translates logical network address and names to their physical address (e.g. computername ==> MAC address) responsible for addressing, determining routes for sending managing network problems such as packet switching, data congestion and routing. if router can’t send data frame as large as the source computer sends, the network layer compensates by breaking the data into smaller units. At the receiving end, the network layer reassembles the data. think of this layer stamping the addresses on each train car.
Data link layer – turns packets into raw bits 100101 and at the receiving end turns bits into packets. handles data frames between the network and physical layers. Network layer responsible for error-free transfer of frames to other computer via the physical layer.
Physical layer – transmits raw bit stream over physical cable,
defines cables, cards, and physical aspects defines NIC attachments to hardware, how cable is attached to NIC defines techniques to transfer bit stream to cable.