Static vs dynamic IP: what's the difference?
A static IP address stays exactly the same every time you connect, while a dynamic IP gets reassigned by your provider — sometimes every session, sometimes only when your router reboots or a lease expires weeks later. Most home and mobile connections are dynamic by default; static is the exception you usually have to request, and often pay for.
How your provider decides which you get
Providers hand out addresses from a pool using DHCP, the same protocol your own router uses internally to assign local addresses to your laptop and phone. Each connection gets a “lease” on an address for a period of time — anywhere from a few hours to several months. When the lease renews, the ISP can hand you the same address again or a different one from the pool, depending on demand and how the pool is managed. Dynamic addressing exists mainly because ISPs have far more customers than spare IPv4 addresses, so recycling unused leases lets them serve everyone without buying more address space. Static IPs skip that recycling: the provider reserves one address and binds it to your account specifically, which costs them a permanently unavailable address just for you.
How to tell which one you have
There is no setting that announces it outright, but the test is simple: check what address the home page shows you right now, then check again in a day or after your router has power-cycled. If the number is identical both times, you almost certainly have a static IP (or a lease so long it behaves like one in practice). If it changed, your connection is dynamic. Running the check over a few days rather than minutes matters, since most dynamic leases don’t expire the instant you reconnect.
Who actually needs a static IP — and what it costs
For everyday browsing, streaming, and video calls, a dynamic address works fine and nobody notices the difference. Static starts to matter when other things need to find you reliably: a home server or NAS you access remotely, a security camera system with remote viewing, an office you allowlist by IP with a bank or vendor, or a VPN endpoint your team dials back into every day. Some dynamic-DNS services paper over the gap by pointing a hostname at whatever address you currently have and updating it automatically, but that adds a moving part and a dependency on a third-party service staying online — it is a workaround, not a real substitute for an address that simply does not change. If your address keeps drifting, all of those break or need re-configuring each time it changes. Residential ISPs commonly sell a static IP as a small add-on, often somewhere in the $5–15/month range; business-tier plans frequently bundle one in already, since commercial customers are more likely to run something that depends on it. Not every ISP offers residential static IPs at all, in which case a business plan is the only route to one.
CGNAT and the privacy trade-off
Asking for a static IP assumes your provider gives you a dedicated public address to begin with — some don’t. Many mobile carriers and a growing number of residential ISPs now place customers behind carrier-grade NAT, sharing one public IP across hundreds of households simultaneously. If that’s your situation, “static vs dynamic” is beside the point: you don’t have an address of your own to make static until you escape CGNAT entirely, typically with a paid public-IP add-on.
Dynamic addressing does have one upside: because the number attached to your household keeps rotating, it’s a moving target rather than a fixed label. As covered in what your IP reveals, an address alone was never enough to identify you personally — but a static one does make your connection easier to recognize and correlate across visits over long periods, which is part of why some privacy-conscious users deliberately stick with dynamic even when static is available and affordable.