Networking and Web Technologies

• Request sent to DNS resolver (finds IP address corresponding to URL) • Resolver checks it’s cache and if it doesn’t find the IP address, it passes it onto TLD name server • IP address is sent back to the client • If not found, an error is sent back

• Direct link between two devices for the duration of the communication e.g. phone calls • no delay in receiving and sending data, and data packets arrive already in order • bandwidth is wasted when no data is being transmitted

• data is broken down into more manageable chunks • packet contains header (IP addresses of sender and recipient, packet number) • payload (actual data being transmitted) • and trailer (checksum - error checking data)

• packets encapsulated in new packet data • application - application being used to transmit • transport - data split into packets, header of order put packets and trailer of port added • internet - IP address of sender and recipient added • link - MAC address of recipient added, so can find computer once teaching network

• Client computers connected to a powerful central computer (server) • better security, centralised management (backups, software) • expensive to set up and manage

• computers are connected to each other (have equal status) and share data • cheap, not difficult to maintain • used in online piracy