Tools of Web Development 1: Internet Protocols

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Tools of Web Development 1Internet Protocols
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Goals

• Understand what a protocol is.
• Understand how TCP/IP works.
• Understand how IP addresses work.
• Understand what domain names are.
• Understand the different protocols available on
  the Internet.

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When Computers Communicate

• When two or more computers communicate, they must
  have a common way in which to communicate.
• To do this computers use protocols
• A protocol is an agreement by which two or more
  computers can communicate.
• Transfer Control Protocol/Internet Protocol is
  the underlying protocol for the Internet.

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How TCP/IP Works

• 1) Transfer Control Protocol (TCP) breaks data
  into small pieces of no bigger than 1500
  characters each. These pieces are called
  packets.

10101010100110101001101001101021010101010101101011
11010101110111011101101100001011101101010101010011
10101001010111101000
101010101001101010011010011
101010101001101010011010011
101010101001101010011010011
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How TCP/IP Works

• 2) Each packet is inserted into different
  Internet Protocol (IP) envelopes. Each
  contains the address of the intended recipient
  and has the exact same header as all other
  envelopes.

101010101001101010011010011
101010101001101010011010011
101010101001101010011010011
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How TCP/IP Works

• A router receives the packets and then determines
  the most efficient way to send the packets to the
  recipient.
• After traveling along a series of routers, the
  packets arrive at their destination.

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How TCP/IP Works

• Upon arrival at their destination, TCP checks the
  data for corruption against the header included
  in each packet. If TCP finds a bad packet, it
  sends a request that the packet be
  re-transmitted.

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IP Addresses

• Since computers process numbers more efficiently
  and quickly than characters, each machine
  directly connected to the Internet is given an IP
  Address
• An IP address is a 32-bit address comprised of
  four 8-bit numbers (28) separated by periods.
  Each of the four numbers has a value between 0
  and 255

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IP Addresses

• Example of an IP Address

http//134.68.140.1/
The IP Address of the Computer Science
Departments Web Server
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IP Addresses vs. URLs

• While numeric IP addresses work very well for
  computers, most humans find it difficult to
  remember long patterns of numbers.
• Instead, humans identify computers using Uniform
  Resource Locators (URLs), a.k.a. Web Addresses.

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IP Addresses vs. URLs

• When a human types a URL into a browser, the
  request is sent to a Domain Name Server (DNS),
  which then translates the URL to an IP address
  understood by computers.
• The DNS acts like a phonebook.

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Anatomy of a URL
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What about Email Addresses?
jstudent_at_cs.iupui.edu
sub-sub domain
domain name
username
sub-domain
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Top Level Domain Names
.edu Educational Institution .gov Governmental
Agency .mil Military Entity .com Commercial
Entity .net Internet Service Provider .org Non-P
rofit Organization
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Internet Protocols
http// World Wide Web mailto E-mail
address ftp// File Transfer Protocol telnet Te
lnet