Private and Public IP Addresses: Difference between revisions

The are two types of Internet Protocol (IP) addresses: '''Public''' and '''Private'''.  

'''Public static''' - some times called '''Dedicated''' - means the IP address never changes and is tied to a single user, device, server or website.  

The example above depicts a scenario where the Internet Service Provider (ISP) provides different routers with IP addresses that are unique and constant (they never change for each device). In this case the router performs the NATing process instead of the ISP, thefore the ISP is "transparent" when the router sends or receives data from remote hosts on the internet.  

'''Public dynamic''' - means the IP address can change from time-to-time (for example, when you lose connection and re-connect or the ISP might change the address periodically).

From the example above we can see that in case of dynamic IP addresses the ISP provides the routers with private WAN IP addresses that are then "translated" into public IP addresses when connecting to remtoe hosts on the internet. The main difference from static IP addresses is that the dynamic IPs provided by the ISP are not permanent. They will change when the router disconnects and reconnects, re-registers to a network operator or, in some cases, the ISP might update the IP addresses periodically.

'''Public shared''' - in some cases, an ISP can assign a public IP address to a group of users, and then employ NAT to isolate their traffic.

In the example above we can see that it is possible for multiple devices (even websites) to share a single public IP address. An ISP provides clients with private WAN IP addresses and then uses NAT to differentiate to which host specific data packets should be directed to.