The Internet

1
The Internet
2
Learning objectives

• To see the extent of the Internet
• Describe how the Internet works
• To learn the major capabilities of the Internet
• To learn how the Internet addressing system works

3
The Internet

• Started with the US Department of Defense
• Grown exponentially since

http//www.isc.org/ds/hosts.html
4
Internet Usage in the UK

• OfCom report Nov 2003 (published Jan 2004)
• 50 UK homes connected to the Internet
• 59 UK homes have a PC
• 68 Small Businesses have Internet Access
• 12 UK homes using broadband
• 3.2 million broadband connections in UK
• Ofcom Research

5
Tim Berners-Lee

• Developed the browser/web server model
• Initially for him-self in 1981
• Then for the world at large in 1991

6
Internet Technology

• The Internet is based on the client/server model
  of computing
• Uses TCP/IP
• Tools include
• E-Mail
• Usenet
• Telnet FTP
• A large proportion of web servers use Apache web
  server software which is open source and free
  from www.apache.com

7
Email

• POP (Post Office Protocol) mail common
• Need user name and password
• Receiving Mail Server (POP3)
• eg. pop.freeserve.net
• Sending Mail Server (SMTP)
• smtp.freeserve.net
• IMAP
• Internet Message Access Protocol
• Message stays on mail server
• Hotmail
• Web based

8
Usenet

• Newsgroups

9
Telnet FTP

• Telnet is used to connect to another computer
  remotely
• Most likely a UNIX server
• FTP (File Transfer Protocol) used to transfer
  files from one computer to another
• Used to upload files from PC to web server for
  web pages

10
The World Wide Web

• The Graphical User Interface (GUI) of the first
  web browser MOSIAC caused the boom in Internet
  usage through the World Wide Web (WWW).
• WWW
• all the resources and users on the Internet that
  are using the Hypertext Transfer Protocol.
  www.whatis.com
• Based on HTML

11
Websites

• Websites start with a home page (index.html or
  home.html)
• Address is held in a uniform resource locator
  (URL) e.g.
• http//www.busmgt.ulst.ac.uk/business/mt/bmg376c1/
  bmg376c1.html
• ulst.ac.uk is the domain name
• ac for academic (function)
• uk for United Kingdom (location)
• http stands for hypertext transport protocol

12
Search Engines

• Yahoo
• More of a listing
• Have to submit to get in
• Not easy
• Google, Lycos, Altavista etc
• Maintain a database of content of pages
• Use different methods to produce search results
• Google for example puts pages that have a lot of
  links to it at the top of their results
• People want to get to the top of searches so that
  their site will attract visits

13
Internet Addressing

• The Internet gets its name from the IP network
  layer protocol
• This defines the format for packets of data that
  are forwarded by routers on the network
• The current system, called IP version 4 (IPv4)
  uses an internet address (IP address) presented
  as four numbers separated by full stops
• E.g 193.61.168.2
• This is known as a 32 bit address (four times 8
  bits) and offers 4,294,967,296 different
  possibilities
• In spite of there only being about 3 billion
  people on the planet, we are actually running out
  of IP addresses, because so many individual
  pieces of electrical equipment are being hooked
  up to the Internet and each one will require its
  own individual IP address

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IP version 6

• This is the solution to the problem
• This has a 128 bit address space and should
  deliver no fewer than 340 trillion trillion
  trillion possible addresses
• Address will use 16 triplets instead of the
  current 4, but will express the numbers in hex
  (base 16) instead of decimals and will use
  colons, not full stops.
• A number of operating systems are IPv6 ready, but
  Microsoft did not address this issue until the
  release of XP.
• IPv6 will take a long time to roll out given the
  laissez-faire nature of the Internet, but the two
  protocols will need to be able to co-exist for
  quire a few years until IPv6 takes over.
• Further info on IPv6 at www.IPV6.com

15
Domain Name System

• The Domain Name System (DNS) exists to translate
  the domain names that humans like into the IP
  addresses which computers like.
• There are two types of top-level domains
• Generic Domains (.com, .org, .net, .edu, .gov,
  .mil, .int)
• Country Code Domains (e.g. .uk, .ie, .jp, .fr,
  .de etc)
• 7 new top-level domains introduced in 2001 and
  2002(.aero, .biz, .coop, .info, . museum, .name,
  .pro)

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.UK Top level domain

• In the UK the .uk top level domain has been
  administered by Nominet UK, a private company
  limited by guarantee since 1 July 1996
• The .uk domain is divided into a number of
  sub-domains co.uk, ac.uk, sch.uk, gov.uk
• Registering a domain name can be done through a
  number of commercial organisations, and the cost
  will vary, but should not cost more than 50 for
  .uk, slightly more for .com.
• Cybersquatting is where somebody registers a name
  hoping to profit by selling it on to the person
  who might expect to have it.
• The courts have usually come down against the
  cybersquatter and forced them to hand over the
  domain.

17
DNS Servers

• When you request a page on the world wide web
  using a domain name this is translated by a DNS
  server into the IP address
• The IP addresses of all the domain names is a
  distributed database stored on a number of
  servers
• There are a number of DNS servers, normally
  geographically close to Internet Service
  Providers.