A public or external Internet Protocol address is one of two types of IP addresses designed exclusively for external interfacing. Meaning it’s used for assisting computers and other kinds of devices with an Internet connection to find one another on the World Wide Web. In other words, any devices on the planet can reach a public IP address – hence the name.
Speaking of monikers, if you ever encounter any mention of a dedicated IP address, know that this term is a third, less commonly used label for external or public IP addresses.
Regardless of how you want to call them, these designations are further divided into static, dynamic, and shared IP addresses.
Static IP addresses
Static, or dedicated IP addresses are pretty self-explanatory: their whole schtick is that they never change. Such addresses are assigned to both clients and servers. A single static IP address can also be assigned to numerous machines, so long as they all constitute a cluster hosting the same website or online app.
The very nature of static public IP addresses makes them inherently less secure as they trivialize the process of tracking their owners across the entire Internet. Nevertheless, they remain a popular choice for remote access setups favoring speed and overall convenience.
Dynamic IP addresses
On the contrary, a dynamic IP address is one that inevitably changes over time. This doesn’t have to mean at regular intervals. On the contrary, the most frequently encountered changes in dynamic IP addresses occur upon client or router disconnections, i.e. re-connections.
Of course, Internet service providers can still change them periodically for security purposes. And even dynamic IP addresses that rarely change are still considered safer than their static counterparts.
Dynamic IP addresses typically show their limitations in scenarios requiring permanent access points for remoting into networks. They can certainly still do their part across enterprise VPN setups and such systems, but only alongside a domain name system (DNS) refresher service. Not to mention that such networking combos usually come at a cost of somewhat slower connection speeds. Granted, that drawback may very well be negligible.
Shared IP addresses
Shared IP addresses are something akin to a hybrid solution. As their name implies, these designations are assigned to numerous clients, hosts, or websites. That technically makes them a risk for individual devices they are assigned to, seeing how the activity of any one of them could be tied to any other.
That aside, shared IP addresses can still be used for resolving individual recipient’s communications, so long as they’re deployed in conjunction with network address translation traversal (NAT T) protocols. Those are leveraged at a local network level for determining which specific client under a single shared IP address is meant to receive any given data packet or group thereof.
While static and dynamic IP addresses are often assigned directly by ISPs, their shared alternatives are typically allocated locally. Of course, any kind of a public IP address can always be spoofed.