Types of IP Address: IPv4 and IPv6 Explained
Every device online needs an address. Here’s how IPv4 and IPv6 work, and how public, private, static, dynamic, unicast, and multicast addresses fit into the picture.
What Is an IP Address?
An IP address (Internet Protocol address) is a number assigned to every device on a network so it can send and receive data. A phone, laptop, printer, or router all get one. Without it, a data packet has no way to know where to go or where it came from. An IP address is a unique numeric label assigned to a device on a network, used to identify that device and route data to and from it. Every packet carries a source IP and a destination IP.
Two versions of this addressing system are in use today: IPv4, which has been around since 1983, and IPv6, built later to fix a problem IPv4 could not avoid: running out of addresses.
IPv4 vs IPv6: Structure and Key Differences
An IPv4 address is a 32-bit number, written as four numbers from 0 to 255 separated by dots, like 192.168.1.15. That format allows for about 4.29 billion unique addresses, which sounded like plenty in 1983 and stopped sounding like plenty once smartphones, routers, and IoT devices showed up by the billion.
IPv6 fixes that by using a 128-bit address, written in hexadecimal and split into eight groups, like 2001:0db8:85a3::8a2e:0370:7334. That gives roughly 340 undecillion addresses, more than enough for every device humanity is likely to build.
| Feature | IPv4 | IPv6 |
|---|---|---|
| Address size | 32-bit | 128-bit |
| Format | Decimal, dot-separated | Hexadecimal, colon-separated |
| Example | 192.168.1.1 | 2001:0db8:85a3::8a2e:0370:7334 |
| Total addresses | ~4.3 billion | ~340 undecillion |
| Security (IPSec) | Optional | Built in |
| Address depletion | Already exhausted at the registry level | Designed to solve the shortage |
Example: A home router might show an IPv4 address like 192.168.0.1 for its local network, while its connection to the ISP could be reachable over IPv6 as something like 2001:db8::1. Most networks today run both side by side, a setup called dual stack.
Public IP vs Private IP Address
Every device with a private IP address sits inside a local network, whether that is a home Wi-Fi setup or an office LAN. Private addresses are not reachable from the open internet on their own; they need network address translation (NAT) at the router to get out. Because private ranges are reserved, the same block of addresses can be reused inside millions of separate networks without conflict.
| Private Range | CIDR |
|---|---|
| 10.0.0.0 – 10.255.255.255 | 10.0.0.0/8 |
| 172.16.0.0 – 172.31.255.255 | 172.16.0.0/12 |
| 192.168.0.0 – 192.168.255.255 | 192.168.0.0/16 |
A public IP address is the one your ISP assigns to your router, and it is what the rest of the internet sees when your traffic leaves your network. Servers, websites, and email hosts all need a public IP to be reachable directly.
Common mix-up: Students often assume “public” means it belongs to one person forever, and “private” means it is somehow hidden or encrypted. Neither is true. Public just means routable on the internet; private just means confined to a local network. Neither term says anything about ownership or security by itself.
Static IP vs Dynamic IP Address
A dynamic IP address changes periodically and is assigned automatically, usually through DHCP (Dynamic Host Configuration Protocol). Most home internet connections work this way. It is cheap to run and easy to manage, and the address rotation is actually a small security plus, since a moving target is harder to track.
A static IP address stays fixed. It has to be set manually, or requested from an ISP, and it usually costs extra. Anything that needs to be reliably reachable at the same address, a website’s server, a mail server, a security camera system accessed remotely, tends to run on a static IP.
Dedicated IP vs Shared IP Address
This distinction applies specifically to website hosting. A dedicated IP address belongs to one domain only. A shared IP address is used by several domains on the same server at once, which is standard on budget hosting plans.
| Dedicated IP | Shared IP | |
|---|---|---|
| Used by | One website | Multiple websites |
| Cost | Higher | Lower |
| Reputation risk | Only your own traffic affects it | Another site’s spam or malware can get the shared IP blocklisted |
| Typical use | SSL certificates that need it, high-traffic sites, direct FTP access | Small blogs, low-traffic sites, most shared hosting plans |
Unicast, Broadcast, Multicast, and Anycast
IP addresses are also classified by how data actually moves once it is sent. This matters more in networking coursework than in everyday browsing, but it explains a lot about how the internet avoids drowning in duplicate traffic.
| Type | How it works | Example use |
|---|---|---|
| Unicast | One sender, one receiver. The default for almost everything. | Loading a webpage, sending an email |
| Broadcast | One sender, every device on the local network receives it. IPv4 only; IPv6 dropped it. | ARP requests on a LAN |
| Multicast | One sender, a specific group of subscribed receivers. | Video streaming, live conferencing |
| Anycast | One address, delivered to whichever receiver is closest on the network. | DNS root servers, CDNs |
Classful IPv4 Addressing (Class A to E)
Before subnetting became the norm, IPv4 addresses were divided into five fixed classes based on the first octet. Most of this is legacy today, but it still shows up in exams and in older documentation.
| Class | Address Range | Typical Use |
|---|---|---|
| A | 1.0.0.0 – 126.255.255.255 | Very large networks (127.x is reserved for loopback) |
| B | 128.0.0.0 – 191.255.255.255 | Medium networks, universities |
| C | 192.0.0.0 – 223.255.255.255 | Small networks, homes, small businesses |
| D | 224.0.0.0 – 239.255.255.255 | Multicast groups |
| E | 240.0.0.0 – 255.255.255.255 | Reserved, experimental |
Quick Revision
- IPv4 is 32-bit and decimal; IPv6 is 128-bit and hexadecimal.
- Public IPs are routable on the internet; private IPs stay inside a local network and need NAT to reach it.
- Static IPs stay fixed and cost more; dynamic IPs rotate and are assigned by DHCP.
- Dedicated vs shared IP is a hosting distinction, not a networking-layer one.
- Unicast is one to one, broadcast is one to all (IPv4 only), multicast is one to a group, anycast is one to the nearest.
- Classful addressing (A to E) is mostly legacy, replaced by classless (CIDR) addressing in modern networks.
Published September 2026. Last verified: September 2026.
