Networks

LAN:

    Local area network, connected set of computers and other devices, each device is called a node.

    Advantages-

        Allows communication between workers, data sharing, sharing peripherals, upgrade easier,

        distributing processing.

    Disadvantages-

        Expertise needed to set up, strong passwords

    Hardware-

        NIC-network interface card, every node needs one to connect with LAN produce electrical signals

        HUB-a device that connects nodes together, makes them act as one unit, all data packets are                           transmitted

    A router forwards data packages between computer networks

    Switches allow nodes to communicate with each other 

    Wireless access point, means no building work needed, flexible, visitors can access but has a       

    Low performance and security issues.

Peer to peer:   Could be slow because of data collisions and shared processor power.

Client server:   One or more computers are the server and they have software, data and peripheral access that it shares, in control of what they can do, records what is used for, extra security and requires a log in.

Topology: physical layout of network

Star topology: shared link to a server, few data collisions, fast and can have independent sections.

Ring topology: all connected by one cable, fast and no collisions as one way traffic but any problems would affect all of them.

Bus topolgy: one linking cable with nodes coming of it, cheap but lots of data collision, slows down in heavy traffic, any problems affect all.

WAN: wide area network, structure could be telecoms companies

VPN: virtual private network, better security, uses Internet.

Protocols: rules for device communication

   DNS: translates domain names into IP adresses

   TS/SSL: secure communications

   FTP: copy files from another host

   Gopher: early way of searching on internet

   HTTP: for web pages

   IMAP: method for accessing emails

   POP3: another way to access emails

   Telnet: text communications on a network

IP adresses: code that identifies the node

MAC: communicate with physical layer of network

Packets: data is put into packets when it needs to go to another adress

Security

   Access levels: uses log in names to grant privileges

   Passwords: must be something that people couldn't guess and should be changed often

   Encryption

Policies: tell users what is expected from them