Revision cs

Revision cs

1. Layers

   • Application
     • Where user can interact with apps and communicate
     • HTTP/S, POP, IMAP, SMTP, FTP, DNS
   • Transport
     • Sets up communication rules
     • TCP
   • Internet
     • Puts data into packers and assigns addresses
     • IP
   • Network
     • Sends packet to receiver
     • Ethernet/ wifi
   • Advantages
     • Reduces complexity
     • Standardised interfaces
     • Facilities modular development
     • Range of developers can contribute
     • Development is faster

2. Roles of Computers

   • Client server
     • Security
       • Server controls security
       • good
     • Management
       • Server manages network
       • Needs dedicated team
     • Dependency
       • clients depends on server
       • if server crashes whole network fails
     • Performance
       • Server can be upgraded to cope with high demand
       • good
     • Backups
       • Data backed on main server
   • Peer to peer
     • Security
       • no central control over security
       • poor
     • management
       • no central control
       • Anyone can set up
       • maintenance more diffucult
     • Dependency
       • Clients not dependent on central server
     • Backups
       • Each computer has to be backed
       • Data can easily be deleted by users

3. Forms of attack

   • Malware
     • Malicious software with intention to cause damage or steal
     • Most common form of attack
   • Phishing
     • Fraud Emails
     • Tricks user to share info
   • SQL injection
     • used to view/ change data by inserting additional code
     • dangerous
   • DDOS
     • Floods server with traffic
     • essentially crashes server
   • Hacking
     • gaining unauthorised access to computer system