An Overview of IPv4 and IPv6 - CompTIA A+ 220-801: 2.3

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
• OSI Layer 3 address
• Groups of zeros can be abbreviated with a double colon ::
• Only one of these abbreviations allowed per address

• Leading zeros are optional
• Your DNS will become very important

IPv6 address shortcut

Public addresses vs. private addresses

• RFC 1918

Automatic Private IP Addressing (APIPA)

• A link-local address
• No forwarding by routers
• IETF has reserved 169.254.1.0 through 169.254.254.255
• Those last 256 addresses are reserve
• IPv6 reserves fe80::/10 (assigned as fe80::/64)

• Automatically assigned
• Uses ARP to confirm the address isn't currently in use

• Check your IP address 
• Is it an APIPA address?