What is a Computer Network?
A network can be defined as a group of computers and other devices connected in some ways so as to be able to exchange data. -Each of the devices on the network can be thought of as a node; each node has a unique address.
Types of Network :
A local area network (LAN) is a group of computers and associated devices that share a common communications line or wireless link to a server.
Cover cities, countries, and continents. -Based on packet switching technology -Examples of WAN technology: Asynchronous Transfer Mode (ATM), Integrated Services Digital Network (ISDN)
Internet address Consists of 4 bytes separated by periods Example: 220.127.116.11 -The R first bytes (R= 1,2,3) correspond to the network address; -The remaining H bytes (H = 3,2,1) are used for the host machine.
Domain Name System (DNS)
Mnemonic textual addresses are provided to facilitate the manipulation of internet addresses. -DNS servers are responsible for translating mnemonic textual Internet addresses into hard numeric Internet addresses
In modern networks, data are transferred using packet switching. -Messages are broken into units called packets, and sent from one computer to the other. -At the destination, data are extracted from one or more packets and used to reconstruct the original message. -Each packet has a maximum size, and consists of a header and a data area. -The header contains the addresses of the source and destination computers and sequencing information necessary to reassemble the message at the destination.