A dynamic IP address is assigned automatically and can change. A static IP address is fixed and stays the same.
Dynamic IP addresses
Dynamic addresses are commonly handed out with DHCP. In DHCP's “dynamic allocation”, an address is assigned to a client for a limited period — a lease — which the client can extend with further requests (RFC 2131). If a lease runs out, the client may be given a different address next time.
Pros: automatic, nothing to configure.
Cons: anything that depends on your IP (allow-lists, remote access) breaks when it changes.
Static IP addresses
A static IP doesn't change. Some ISPs offer one, often on business plans or for an extra fee — ask yours.
Pros: reliable for hosting servers, VPN endpoints, remote access and IP allow-lists.
Cons: may cost extra, and it's a stable identifier for your connection.
| Dynamic | Static | |
|---|---|---|
| Changes? | Can change (e.g. when a DHCP lease runs out) | No |
| Setup | Automatic | Arranged with your ISP, or configured manually |
| Best for | Everyday browsing, streaming, gaming | Servers, remote access, allow-lists |
Do I need a static IP?
Usually only if other people or systems need to connect to you. Alternatives:
- Dynamic DNS (DDNS) — a hostname that's updated to point at your current IP. Check whether your router has a DDNS setting.
- Tunnels — Cloudflare Tunnel connects your services to Cloudflare without needing a publicly routable IP address.
To detect when your IP changes, compare the output of curl https://forgotmyip.com over time — see Get your IP from the command line.
Fixed IPs on your home network
Inside your network you can give a device (a printer, NAS or game console) a fixed private IP. In DHCP's “manual allocation”, the administrator chooses a client's address and DHCP delivers it to that client (RFC 2131, §1). In a router's admin page this is often labelled a DHCP reservation or similar.