1. comp101 Lecture ‘Internet’ abstract 1 What is the Internet? The US military wanted a network that was robust under enemy attack. US academics wanted a network that would allow researchers to share information and computing resources. Their joint efforts resulted in ARPAnet. ARPAnet was launched in 1969 Internet is: A global interconnected network of computer networks plus the information held in those networks.

2. comp101 Lecture ‘Internet’ abstract 2 Rules and conventions: Addresses Every computer that is directly connected to the Internet has two addresses. The formal address is the four number IP address (e.g. 139.80.91.23). The informal (‘human’) address is the hostname (e.g. atlas.otago.ac.nz). A Domain Name Server (DNS) translates between the two. The human address may have an alias (e.g. cs.otago.ac.nz for atlas.otago.ac.nz).

3. comp101 Lecture ‘Internet’ abstract 3 Rules and conventions: Domain Names What means atlas.otago.ac.nz? Part after leftmost ‘.’ is called domain name. Highest level (rightmost) is the country code or country domain (.nz: New Zealand). Next level is more properly called the ‘domain’ (of interest) (.ac: academic). Below, the institution or subdomain (.otago). Finally the machine or local identifier (atlas). In the USA the highest level is the ‘domain’:.com,.edu,.gov,... Country code not used.

4. comp101 Lecture ‘Internet’ abstract 4 Rules and conventions: Internet Protocols — TCP/IP TCP = Transmission Control Protocol Controls correct transmission of a message chopped up in packets IP = Internet Protocol Controls the routing from source to destination node. Use the IP addressing system of the Internet

5. comp101 Lecture ‘Internet’ abstract 5 Internet Services Electronic mail and mailing lists Newsgroups Telnet (remote login) and ftp (file transfer) Real-time communication World Wide Web