IPv6

IPv6 - 128 bit address space ( 8 groups for 4 hexadecimal digits separated by colon ) 

IPv4 - 32 bit ( 4 groups of integers between 0-255 separated by colon )

Concept of private networks helped dealing with scarcity of IP addresses in the IPv4 protocol. Machines on private network did n't have its own public IP but rather used NAT server for this. 

NAT - Network Address Translation. It is used for facilitating communication from machines on privates networks to the Internet. As machines on private networks don't have public IP, they go throw NAT ( router or firewall ) which takes private source IP and assigns its own public IP address to the traffic and sends to the external public IP. Does the reverse to the reply which comes back to it from external system.



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