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Public vs. Private IP (IPv4)

The Internet Assigned Numbers Authority (IANA) defines specific IPv4 address ranges for private use within LANs and public use on the Internet.

Private IP Ranges

Reserved for internal network communication and not routable over the public Internet.

10.0.0.0 – 10.255.255.255

CIDR: 10.0.0.0/8

Common in large enterprise or multi-site networks.

172.16.0.0 – 172.31.255.255

CIDR: 172.16.0.0/12

Frequently used in AWS VPCs (default VPC CIDR often in this range).

192.168.0.0 – 192.168.255.255

CIDR: 192.168.0.0/16

Popular in home routers and small office LANs.

Public IP Addresses

Any IPv4 address outside the private ranges.

Routable on the public Internet.

Required for direct communication between AWS resources and external networks unless a NAT Gateway or proxy is used.