The Network Topology 
                             Component
                                DMZ
                                           Host         Host
                                              Host
                                                         Host
           Internet
                         Firewall                Hub
                  Router          Switch
                                                         Host
                                             Printer
                                         Radius Server
                         Network Component
           •    Router: A router is a device utilised to route or 
                forward data between two separate networks.
           •    Firewall: security device (both hardware and 
                software) that is used to restrict access in 
                communication networks. 
           •    Switch: device that connects devices together on a 
                computer network by using packet switching to 
                receive, process, and forward data to the destination 
                device.
                         Network Component
           •    Host: An intelligent device that stores or processes 
                information in various forms, which should be 
                configured or managed regardless of whether an end-
                user interacts directly with the device.
           •    Hub: networking device that connects multiple 
                computers or other network devices together
           •    RADIUS: Remote Authentication Dial in User Service 
                (RADIUS) is a network protocol which provide access, 
                authorisation and accounting management controls.
                              Hub vs Switch
                                 Hub                      Switch
          Layer       Physical layer. Hubs are   Data Link Layer. Network 
                      classified as Layer 1 devices  switches operate at Layer 2 
                      per the OSI model.         of the OSI model.
          Function    To connect a network of    Allow to connect multiple 
                      personal computers         device and port can be 
                      together, they can be      manage, VLAN can create 
                      joined through a central   security also can apply
                      hub.
          Ports       4/12 ports                 24/48 ports
         Firewall – What is it?
    A firewall is a device (or software feature) designed to 
    control the flow of traffic into and out-of a network.
    In general, firewalls are installed to prevent unauthorised 
    computer  access  between  networks,  or  networks  and 
    applications, and only allow access to services that are 
    expressly registered.