IP What is an IP Address?
An IP address identifies a device on a network. Learn the difference between public and private IPs, IPv4 vs IPv6, and static vs dynamic assignment.
What is an IP address?
An IP address (Internet Protocol address) is a numerical label assigned to every device connected to a network that uses the Internet Protocol for communication. It serves two purposes: identifying the device (who you are) and indicating its location in the network (where you are).
There are two versions in active use: IPv4 (32-bit, written as four decimal octets like 192.168.1.1) and IPv6 (128-bit, written as eight hexadecimal groups like 2001:db8::1).
Public vs. private addresses
Not all IP addresses are reachable from the open internet. Three ranges are reserved for private networks (RFC 1918) and are never routed on the public internet:
| Range | CIDR | Addresses | Common use |
|---|---|---|---|
10.0.0.0 – 10.255.255.255 | 10.0.0.0/8 | 16,777,216 | Large corporate networks, VPNs |
172.16.0.0 – 172.31.255.255 | 172.16.0.0/12 | 1,048,576 | Cloud VPCs, data centres |
192.168.0.0 – 192.168.255.255 | 192.168.0.0/16 | 65,536 | Home routers, small offices |
Your home router has one public IP (assigned by your ISP) and hands out private IPs to your devices via DHCP. Network Address Translation (NAT) lets all those private devices share the single public IP when communicating with the internet.
Special addresses
| Address | Purpose |
|---|---|
127.0.0.1 | Loopback — always refers to the local machine (localhost). |
0.0.0.0 | Unspecified address — used in routing to mean "all addresses" or "no address". |
255.255.255.255 | Limited broadcast — sent to all devices on the local network segment. |
169.254.x.x | Link-local — auto-assigned when DHCP fails (APIPA). Not routable. |
Dynamic vs. static addresses
A dynamic IP address is assigned by a DHCP server and may change over time. Most residential internet connections and devices on a network use dynamic IPs — they're efficient because addresses are reused when devices disconnect.
A static IP address is fixed and doesn't change. Servers, printers, and other infrastructure often use static IPs so they're always reachable at the same address. Web servers need static public IPs (or at least a stable DNS record updated automatically via dynamic DNS).
Frequently asked questions
How do I find my public IP address?
Visit pingfloat.com/tools/whats-my-ip/ — it shows your public IP along with country, city, and ISP information.
Can two devices have the same IP address?
Not on the same network at the same time — it causes an IP conflict and connectivity issues. However, private IPs (like 192.168.1.1) repeat across millions of separate private networks worldwide, and NAT keeps them isolated.
What is NAT?
Network Address Translation (NAT) lets multiple devices with private IP addresses share a single public IP address. Your router performs NAT — it tracks which internal device made which request and routes replies back correctly.