IPv4 and IPv6 Addressing

The IP address of a device
  • IP Address, e.g., 192.168.1.165
    • Every device needs a unique IP address
  • Subnet mask, e.g., 255.255.255.0
    • Used by the local workstation to determine what subnet it's on
    • The subnet mask isn't (usually) transmitted across the network
  • You'll ask for the subnet mask all the time
    • What's the subnet mask of this network?
The secret behind the IP address
  • The IP address isn't really a single address.
  • An IP address is a combination of a network ID and a host ID
    • The subnet mask determines what part of the IP address is the network and which part is the host
    • The subnet mask is just as important as your address!
  • The best way to see this work is in binary
    • This is the (very easy) math part
IPv4 addresses - Internet Protocol version 4
  • OSI layer 3 address
  • Since one byte is 8 bits, the maximum decimal value for each byte is 255


IPv6 addresses
  • Internet Protocol v6 - 128-bit address
    • 340,282,366,920,938,463,463,374,607,431,768,211,456 addresses (340 undercillion)
    • 6.8 billion people could have 5,000,000,000,000,000,000,000,000,000 addresses each
IPv6 address compression
  • Your DNS will become very important!
  • Groups of zeros can be abbreviated with a double colon
    • Only one of these abbreviations allowed per address
  • Leading zeros are optional

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