How IP Addresses Work
Static vs. Dynamic IP Addresses
Ever noticed your IP address changed without you doing anything? That's because most connections use dynamic addresses that are reassigned over time.
Dynamic IP addresses
A dynamic IP address is assigned automatically and temporarily. Your ISP keeps a pool of addresses and leases one to your connection; when the lease expires or your router reconnects, you might get a different address. Most home internet connections are dynamic.
Dynamic addressing is efficient. An ISP does not need a permanent address for every customer — only enough for those online at once — and it can reassign freed addresses to others.
Static IP addresses
A static IP address stays the same over time. It is manually assigned and does not change unless someone changes it. Businesses often pay extra for a static public IP because certain services need a stable, predictable address.
When you want a static IP
- Hosting a server — a website, mail server, or game server that others must reliably reach.
- Remote access — connecting back to your home or office network from elsewhere.
- Whitelisting — services that only allow known, fixed addresses.
When dynamic is fine (or better)
For everyday browsing, streaming, and gaming, a dynamic IP is perfectly adequate — you are the one initiating connections, so your address does not need to be predictable. A changing address even offers a small privacy benefit, since you are not permanently tied to one identifier.
Static inside, dynamic outside
Note that "static" and "dynamic" apply separately to private and public addresses. Many people set a static private IP for a device inside their network (so port forwarding keeps working) while still having a dynamic public IP from their ISP. If you check your address on IP Ducky and it differs from last month, a dynamic public IP is almost certainly why.