3e Network components and Servers

3e Network components and Servers

1. Servers

   • File servers
     • Stores users and shared files on a network. Usually a set amount of storage set for each user.
   • Proxy Servers
     • Manages internet access
       • Stores visited webpages in cache for faster access for next visit
       • Filter access to webpages to block unwanted pages
       • Firewall to examine data and block undesirable data
   • Application Servers
     • Stores software to be used across network
       • Store software so it can be run from server by client's computer
         • Increases network traffic but saves storage, memory and processing on client
       • Store installation files to deploy software to client computers.
         • Reduces traffic but increases storage and processing needed on client computer
   • Mail Servers
     • Manages all email for an organisation
       • Receives all mail and puts each in appropriate inbox
         • Only authorised user can view mail
       • Virus check and SPAM filter
       • Provides central address book
       • Sets mailbox size limits
     • Sends email through LAN or WAN
   • Print Server
     • Manages access to printers
       • Can restrict access to printers or number of pages to be printed at once
     • Send jobs to be processed by printer servers reducing amount of processing by client computer
     • Put print jobs into queue and can prioritise jobs
     • Can charge users and provide report on who printed what
   • Back up Server
     • Backs up all data on network so users don't have to.
     • Schedules backup jobs can be done overnight each day

2. Switch

   • Connects several devices together through ports to enable devices to communicate. Devices are connected to serve by cable
   • Data packets are received and analysed by switch and sent to correct destination port
   • Core Switch
     • Several switches connected to a core switch
     • Core switch manages all data packets received by switch and can send data between switched
     • Used in large organisations
   • Bandwidth can be limited or priority given to data on certain ports
     • Configuring for Quality of service (QoS) to give priority to applications that need guaranteed bandwidth e.g. video conferencing
   • Can be configured to set up VLAN or monitor traffic

3. Hubs

   • Like a switch but doesn't examine data packets
   • Data packets sent to all ports and filtered individually by each device
   • More collisions and more susceptible to interception

4. Wireless Access Point (WAP)

   • Communicates wirelessly with radio signals
   • Usually connected to main network through cable to a switch
   • Recipient devices need to be wirelessly enabled e.g. laptops, mobile phones
   • Signals from wireless devices received and sent to network or another wireless device
   • Easier for hackers to intercept
     • WAPs have to use encryption

5. Network Interface Card (NIC)

   • Enables a computer to be connected to a network using cable
   • Usually automatically included on motherboard as part of computer circuitry
   • Has a Media Access Control (MAC) address to uniquely identify the device
   • Wireless Network Interference Card
     • Used by device in order to communicate to WAP
     • Can be part of internal circuitry, be in the form of a USB wireless dongle or and adapter card

6. Router

   • An advanced switch
   • Store address of devices
   • Uses headers and tables to send data to device in the most efficient route
   • Acts as a gateway for a network

7. Repeater

   • Repeats signal over regular distance to prevent the signal from deteriorating
     • Used on cables, but can be wireless

8. Gateway (application)

   • The exit of one network and entrance of another - Creates a bridge between two networks
     • Is part of a router, switch or proxy server
   • Used to send data from LAN to WAN

9. Firewall (application)

   • Configured on a computer or network to present unauthorised access to or from a network
   • Can be part of router, proxy sever or PC
   • Examines all data coming in or going out of a network and blocks access to unacceptable traffic
   • Can use application gateway to allow or deny certain application traffic e.g. email or file transfer
   • Can be used to only give access to certain users
   • Prevents hackers, viruses or worms getting access to LAN