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What Is an IP Address? Public, Private, Static and Dynamic Explained

An IP address is the number that identifies a device on a network so data can find it — like a postal address for computers. How IPv4 and IPv6 addresses look, public vs private addresses, static vs dynamic, how domains point to them, and why your server needs a stable one.

An IP address is a number that identifies a device on a network, so data knows where to go. Every phone, laptop and server connected to the internet uses one. When you visit a website, your computer looks up the site's IP address and sends its request there.

Think of it as a postal address for computers. A domain name like example.com is the friendly name; the IP address is where the post actually goes. (What Is a Domain Name?)

What one looks like

There are two versions:

  • IPv4: four numbers from 0–255 separated by dots, like 203.0.113.42. There are only about 4.3 billion possible addresses, and they ran out years ago.
  • IPv6: much longer, written in hexadecimal groups, like 2001:db8:85a3::8a2e:370:7334. There are enough for every device ever made, many times over.

Most of the internet runs both side by side. (IPv4 vs IPv6)

Public vs private addresses

  • Public IP: reachable on the internet. Your server needs one so visitors can reach it. Your home router has one too.
  • Private IP: only meaningful inside a local network, such as 192.168.1.20 or 10.0.0.5. Your laptop at home has a private address; the router translates (NAT) so many devices can share one public address.

Private ranges for IPv4 are 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. If an IP starts with one of those, it isn't reachable from the internet directly. (CIDR Notation Explained)

There's one special address you'll meet constantly: 127.0.0.1, which always means "this computer". That's localhost.

Static vs dynamic

  • Dynamic IP: can change from time to time. Most home internet connections work this way.
  • Static IP: stays the same. Servers need this, because your domain's DNS record points to a specific address — if it changes, your site disappears until DNS is updated.

Cloud providers usually give servers a stable public IP (sometimes called a reserved, floating or elastic IP).

How a domain finds an IP

When you type yourapp.com:

  1. Your computer asks a DNS server, "What's the IP for yourapp.com?"
  2. DNS answers with the address in your domain's A record (IPv4) or AAAA record (IPv6).
  3. Your browser connects to that IP.

So "pointing your domain at your server" means putting your server's IP address in an A record. (DNS Records Explained)

How to find yours

  • Your computer's public IP: search "what is my IP" or run curl ifconfig.me.
  • Your computer's private IP: ipconfig on Windows, ip addr on Linux, System Settings → Network on Mac.
  • A domain's IP: nslookup yourapp.com or dig yourapp.com.

Is it private information?

Your IP reveals roughly where you are (often city-level) and your internet provider, not your name or home address. Websites see it every time you visit. A VPN hides it by routing your traffic through another address.

The summary

  • An IP address identifies a device on a network so data can reach it.
  • IPv4 is short and scarce; IPv6 is long and plentiful.
  • Servers need a public, stable IP; your domain's A record points to it.

EasySpawn gives each server a stable address and tells you exactly which DNS records to add for your domain, then sets up HTTPS once they resolve. See how it works or join the waitlist.

Related: What Is a DNS Server? · Ports Explained · Anatomy of a URL · What Is a Server?

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