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    Router: A device that connects different networks and directs data packets
                        between them based on their IP addresses.

                                        Network repeater: A device that boosts incoming electrical, wireless or optical

                                      signals. It amplifies signals to prevent them from becoming too weak or corrupted
                                      during transmission.

                          Gateway: A device that connects dissimilar networks those using different
                        protocols. A gateway takes data from one system, interprets it and
                        transfers it to another system.

                                                  Bridge: A device that connects similar networks, usually LANs using
                                                  the  same  hardware and protocols.  It  reduces  the  traffic  on  other
                                                  network segments as it filters the data based on the MAC addresses
                                                  of the source and destination before forwarding it.

                                         Imagine  computer  networks  as  highways  in  the  sky. What  kinds  of  vehicles  would
                                         travel on these highways and what destinations would they reach?

                                DATA COMMUNICATION SYSTEM

                      Data communication is the process of exchanging data between two devices.

                            Sender                                    Message                                 Receiver

                                                                Transmission Medium
                                   Rule 1, Rule 2, ... Rule n                              Rule 1, Rule 2, ... Rule n
                                         Protocol                                                Protocol

                      There are five main components in a data communication system:

                         Message: This refers to data or a piece of information that is to be communicated.
                         Sender: This is a source in a data  communication  system.  It is a device  that  sends a
                        data message.

                         Receiver: This is the destination of the final message sent by the source. It is a device that
                        receives messages.

                       10   Premium Edition-VIII

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