Introduction to TCP/IP, the Internet, IP Addressing, and Domain Name

Internet

• The Goliath of all computer networks• Links hundreds of millions of computer users

throughout the world

Internet

• A Network of Networks• Tens of thousands of separate computer

networks – All interlinked

Internet

• “a loosely organized international collaboration of autonomous, interconnected networks.”– IETF (Internet Engineering Task Force)

Internet

• Loosely Organized: – No single organization controls it– No control over what content or service appears– Any kind of material imaginable is present– No guarantee of information accuracy

Internet

• International: – At least 192 countries represented

Internet

• Collaboration: – Internet exists because of cooperation among

many different organizations – Collaboration of programmers throughout the

world

Internet

• Interconnected– Concept of Interconnection – Using standard protocols to enable networks to

communicate with each other. – Provided by TCP/IP Protocol

TCP

• Transmission control protocol• Communication between applications• A communication request is sent • “full-duplex” communication• Communication line is occupied between the

two computers

IP

• Internet Protocol• “Connection-less” communication protocol• Messages or other data are broken up into

small independent “packets” and sent between computers via the Internet

• IP “routes” each packet to correct destination

IP Routers

• “Routing” the packet to the correct destination, directly or via another router.

• Router: responsible for right addressing– Depending on traffic volume– Errors in the network– Etc..

Connection-less analogy

• Sending a long letter as a large number of small post cards

RECEIVER

TCP/IP

• TCP and IP working together

TCP IP

Takes care of communication between

Your application software and your network software

Other computers

Responsible for Breaking data into IP packets before they are sent, and assembling packets when they arrive

Sending the packets to the correct destination

IP Addresses

• Each computer must have an IP address before it can connect to the internet

• Each IP packet must have an address before it can be sent to another computer

This is an IP address: 192.68.20.50This might be the same IP address: www.fark.com

IP Address

• Contains 4 numbers• Each computer must have a unique IP address• My IP Address: 120.28.219.91• Uses 4 numbers to address a computer

(between 0 and 255)• 4 numbers separated by a period

Domain name• A name is much easier to remember than a 12 digit

number.• Names used for TCP/IP addresses are called domain

names.• wordpress.com is a domain name.• When you address a web site, like

http://www.wordpress.com, the name is translated to a number by a Domain Name Server (DNS).

• DNS servers are connected to the Internet. DNS servers are responsible for translating domain names into TCP/IP addresses.

Examples of Domain Names

• www.howstuffworks.com - a typical name• www.yahoo.com - the world's best-known name• www.mit.edu - a popular EDU name• encarta.msn.com - a Web server that does not

start with www• www.bbc.co.uk - a name using four parts rather

than three• ftp.microsoft.com - an FTP server rather than a

Web server

Parts of a Domain Name

• Top-level domain or First-level domain– COM, EDU, GOV, MIL, NET, ORG, INT– Unique two letter combination for every country

• Second-level domains– e.g. for COM first level domain:– Howstuffworks– Yahoo– msn– Microsoft, etc..

Parts of a Domain Name

• Third-level domain:– bbc.co.uk

• Up to 127 levels are possible• Host name– Specifies name of a specific machine (with a

specific IP address) in a domain.– E.g. www or encarta

Domain names need to be unique

• Network Solutions– Company responsible for maintaining a list of

unique COM domain names

• Register a Domain Name – Goes through several registrars who work with

Network Solutions– Keeps the whois database. Info of owners and

name servers for each domain.

SEATWORK

• What is the Goliath of All Computer Networks?

• What does TCP mean? What does IP mean?• Each of the four numbers in an IP address is from the

range of numbers between __ and __, inclusive

• What is another name for First-level domain?

• What countries do these first-level domains represent?.tw, .ph, .mx, .dk