Unit 3 Network

Unit 3 Network

1. Protocol

   • a network protocol defines rules for data transmission
     • http / https
       • hypertext transfer protocol
     • FTP
       • file transfer protocol
     • smtp
       • sending email
     • POP and IMAP
       • recieves emails
         • POP will download every new message to your device and no longer available on the server
         • IMAP will leave the messages on a server, they can be accessed by multiple devices and they only are removed if the user deletes them
     • TCP / IP
     • layer
       • a divison of network functinality
       • advantage
         • it is self contained
           • allow different developers to concentrate on one aspect of the network

2. LAN / WAN

   • Wide Area Networks
     • large geographical area
     • uses external network infrastructure
   • Local Area Networks
     • small geographical area
     • uses internal network infrastructure

3. Client Server

   • client server
     • role of client
       • the client sends request to the server
         • waits for a reply
           • receives the reply
     • role of the server
       • the server waits for requests from the client
         • performs any processing required to fulfil the request
           • the requested data is sent back to the client
     • client servers
       • security is controlled by a central server
       • a central backup server backs up all file servers
       • all users are reliant on the central server
     • file servers
       • hold and maintain user files