Internet Access Fundamentals

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Internet Access Fundamentals
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Protocols

• IP (Internet protocol)
• Number or address which identifies each device on
  the internet
• 190.240.100.5
• TCIP (Transmission Control Protocol)
• Assures that data transported with IP arrives
  intact
• How do I find it?
• PC-gt Command Prompt then type ipconfig
• Mac OS9.x -gtControl Panel / TCP/IP
• Mac OS X -gt System Preferences / Network / TCP

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Protocols

• HTTP (Hyper Text Transport Protocol)
• The way elements are linked on a web page
• Web server interprets HTTP
• Web client (browser) interprets HTML

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TCP/IP

• TCP does this
• Breaks up the whole request into packets
• Counts the number of packets and remembers their
  order
• Turns the data packets over to IP
• IP gets the information from the sender to the
  receiver
• TCP puts the information back in the right order

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Data Packet Header

• TCPs Job
• File identification
• Port number (80 or 8080)
• A sequence number
• Checksum number to see if all packets have been
  delivered
• Sends the packet to IP

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Data Packet Header

• IPs job
• Finds the best route to the destination computer
• Sends the data packet back to TCP for reassembly

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Addressing

• Class A
• 1.0.0.0 - 126.0.0.0 (only 126 networks)
• Provides 16 million IP addresses
• Class B
• 128.1.0.0 - 191.254.0.0 (65,536 networks)
• Class C
• 192.1.1.0 - 223.254.254.0 (254 networks)
• Proxy Address
• 10.x.x.x

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DNS

• Domain Name Server
• Translates words into numbers
• Like using a persons phone number instead of
  their name
• Domains are assigned by InterNIC
• Suffixes

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Application Protocols

• FTP
• File Transfer Protocol sends whole files to
  another computer
• HTTP
• SMTP
• Simple Mail Transfer protocol (email)
• Transfers mail between servers on a network
• Mailbox on the corner

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Application Protocols

• POP
• POP 3 account
• Post Office Protocol
• Mailbox on your front door
• IMAP
• Interactive Mail Access Protocol
• Allows access to mail server directories from any
  computer

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Application Protocols

• NNTP
• Network News Transfer Protocol
• Access to news groups

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Process used by SMTP

• Where is the machine that handles
  mail_at_postmaster_at_whatever.co?
• What is the address for that name?
• TCP connection opened on port 25 (socket) on the
  server at that address
• Messages are retrieved / sent