1. Chapter 3 Fluency with Information Technology 4th edition
by Lawrence Snyder
(slides by Deborah Woodall :

2. Network Defined computer network
Two or more computer systems that can communicate with each other over some communications media.
communications media may be classified as
wired - telephone lines, coax, fiber optic
wireless - microwave, satellite

3. Far and Near LAN – Local Area Network WAN – Wide Area Network
The Internet – A global network of Wide Area Networks

4. Classifying Communication
Communication can be classified as either…
asynchronous – sending and receiving occur at separate times
synchronous – sending and receiving occur at the same time

5. Classifying Communication
Also
Communication can be classified as either…
broadcast – one sender, many receivers
multicast – one sender, many selected receivers
point-to-point – one sender, one receiver

6. Communication Classifications
In one way or another the Internet offers all of these forms of communication.
The Internet is truly a universal communications medium.

7. The Client/Server Structure
Most encounters on the Internet reflect the client/server structure.
client: (e.g. your browser)
requests a service (like a Web page)
server: (e.g. Web Server)
provides a service (like sending a Web page)

8. The Client/Server Structure
A client and a server have one or more BRIEF relationships.
An advantage: The server can handle many clients in a short period of time.

9. IP Addresses
Every transmitted message on the Internet requires a destination address
IP address – the address of a computer connected to the Internet

10. IP Addresses
Each IP address is a series of 4 numbers separated by dots, e.g.
Each of the 4 numbers takes up one byte of memory, so an IP address is a 4 byte address.

11. IP Addresses
The IP address from the previous slide would look like this when stored in RAM

12. IP Addresses
How many numbers will fit into one byte?

13. IP Addresses
What would be the range of one of the numbers in an IP address?

14. IP Addresses Why is each of the following an invalid IP address?

15. IP Addresses
And finally, how many IP addresses are possible using the current scheme?
232 >4.3 billion
There is an upgrade being planned for IPv4 called IPv6 – a 16 byte IP addressing scheme - e.g.
69DC:77AC:FF66:A1A2:BCDF:77AC:FF66:3459

16. IP Addresses Your PC has an IP address when connected to the Internet
temporary if connected by modem
permanent (or temporary) if connected to a LAN
Computers deal with numbers but humans don’t do very well remembering numbers.

17. Domain Names A domain is a related group of networked computers.
A domain name is a symbolic name for a 4-byte IP address, and thus a particular computer on the Internet.

18. Domain Names An example: www.mc.edu www is a specific computer
in the mc domain
of the edu domain
A domain name reveals a hierarchy.

19. Domain Names
edu mc
www
sandbox
oak

20. Domain Names Original top-level domains Newer top-level domains .edu
.org
.net
.mil
.gov
.com
Newer top-level domains
.biz (businesses)
.info (information)
.museum (museums)
.name (individuals)
.pro (credentialed professionals)
country codes

21. Domain Names The purpose of a top level domain name is to indicate
Function, or
Location

22. The Domain Name System DNS Servers We like www.jvim.com
Computers like
Where does your browser get the IP Address for a domain name?
DNS Servers

23. TCP/IP
Once the address of the computer is found, how is the message actually sent over the Internet?
TCP/IP
TCP/IP protocol specifies that the message is broken into pieces and each piece goes into a packet.

24. TCP/IP Each packet contains Each packet is independent.
A piece of the message being sent
The destination address for the packet
The source address of the packet
A collating number
Each packet is independent.

25. Ethernet How is a message sent over a LAN? Ethernet Protocol
Ethernet also uses packets.
Ethernet is a true broadcast medium.

26. Connecting to the Internet
How are computers connected to the Internet?
Connect to an Internet Service Provider (ISP) e.g. bellsouth.net, comcast.com, earthlink.net
56K dial-up modem
DSL
Cable modem
Satellite
Cell phone
Connect through a campus or enterprise network.

27. The World Wide Web The WWW is not the same as the Internet.
The WWW is a subset of the Internet.
The WWW is made up of Web servers and their files (Web pages and associated files).
Web pages are NOT stored as bytes of pixel data but as a description of the page.
The WWW is organized hierarchically.

28. stands for Hypertext Transfer Protocol
stands for Hypertext Transfer Protocol
tells the computer how to handle the file
indicates this is a Web page

29. represents the IP address of the server (a computer)
the domain name
represents the IP address of the server (a computer)
specifies a hierarchy from specific to general
(www is a computer in the mc domain of the edu domain)
not case sensitive

30. the path name telling which page and where it is on the server
campus/clubs/acm/members.html
the path name telling which page and where it is on the server
specifies a hierarchy from general to specific
(in the campus folder is a clubs folder containing an acm folder containing a Web page file called members.html)
may be case sensitive

31. Wrap Up
mc.edu vs.