Fixed or Changing Address: Static and Dynamic IPs Compared
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In the static IP vs dynamic IP comparison, a static IP is a public address that stays the same through reboots and reconnects, while a dynamic IP is handed out by your internet provider and can change whenever the connection is re-established. Most home broadband and mobile data plans are dynamic; you need a static address to host something reachable from outside, to sit on an allow-list, or to have accounts sign in from one consistent IP.
Why your address changes at all
Internet providers have far more customers than spare public addresses, especially IPv4 ones. Rather than reserve an address per subscriber, they lend addresses from a shared pool and take them back when a connection ends. That lending model is what "dynamic" means.
A static IP breaks the pattern: the provider sets one address aside for a single subscriber or server and keeps it there. Because it never moves, other systems can rely on it.
Static IP, defined
A static IP is assigned once by your internet or infrastructure provider and stays attached to your line or server. Every outbound connection carries the same address, today and next month.
Two things follow from that. Others can reach you at a known address, which is how a website, a remote camera or a game server is found. And services can trust you by address, adding it to an allow-list once instead of every time you reconnect.
Dynamic IP, defined
A dynamic IP comes from the provider's pool automatically, usually via DHCP or PPPoE. Restart the modem, lose the line or let the lease run out, and you may come back with a different address. 4G and 5G networks reassign even more often.
Many providers add CGNAT on top: a large group of subscribers shares one public address. In that case the IP websites see is not yours alone, and inbound connections to your line are effectively impossible.
The differences that matter
| Static IP | Dynamic IP | |
|---|---|---|
| Behaviour over time | Never changes | May change on reconnect |
| Assignment | Reserved for one subscriber | Lent from the provider's pool |
| Reachable from outside | Yes, with the right ports open | Difficult, almost impossible behind CGNAT |
| Shared with strangers | No | Possibly, under CGNAT |
| Allow-lists | Set once, keep working | Must be updated after every change |
| Price | Usually an extra charge | Included in the plan |
| Where you find it | Servers, offices, static proxies | Home broadband, mobile data |
Find out which one you have
- Load What is my IP and write the address down.
- Restart your modem, wait until you are online again and reload the page. A new address means your IP is dynamic.
- Log in to the modem and compare its WAN address with what the website showed. A mismatch, or a WAN address inside
100.64.0.0/10, means you are behind CGNAT. - Put the address into IP lookup to see the provider and ASN that own it.
Cases where a fixed address pays off
- Hosting a website, game server, NAS or camera that you open from elsewhere.
- Signing in to admin panels, partner APIs or corporate systems that accept only allow-listed IPs.
- Running social, ad or store accounts that should log in from the same place every day. See multi-account work and social media management.
- Sending mail from your own server, where deliverability follows the IP's reputation.
Two routes to a static IP
Buy one from your internet provider. Business plans frequently include or offer a static address. This is the only route if you must accept inbound connections on your own line, for example to host a server at home.
Rent a static proxy. A static proxy gives the software you configure a fixed outbound address in a country of your choice, with no change to your internet plan. It is outbound only: websites see the proxy's IP, but nobody can connect in to your machine through it. For account work that limit does not matter, because what platforms track is the address you sign in from.
Static proxies come in two flavours
ISP addresses are registered to consumer providers, so lookups name a telecom. Datacenter addresses belong to hosting networks; they cost less and are fast, which suits tools and scraping. The trade-offs are covered in ISP vs datacenter vs residential.
At ProxyV4, static ISP proxies are available in the United States and Vietnam, and private IPv4 in seven countries. Each address belongs to one customer, holds steady for the whole rental, and carries over when you renew before expiry. For the opposite model, where the address changes constantly, read static vs rotating proxies.
Frequently asked questions
Does a static IP make me more secure?
No. A fixed address is easier to probe over time, so anything reachable on it needs a firewall and strong passwords. The benefit of a static IP is predictability, not protection.
How long does a dynamic IP last?
It varies by provider. Some keep the same address for days as long as the modem stays on; others change it on every reconnect. Mobile networks often reassign it each time mobile data is toggled.
Is a static proxy equivalent to a static IP from my ISP?
For outbound traffic, yes: the address sites see does not change. The differences are that a proxy covers only configured software and does not accept inbound connections. Hosting a server at home still needs a static IP from your provider.
How can I force a new dynamic IP?
Restart the modem, or toggle airplane mode on a phone. That gives you a new local address, not a new country; for an IP elsewhere, use a proxy or a VPN. See proxy vs VPN.
Can I get a static IP on 4G?
Standard 4G plans use dynamic addresses, usually behind CGNAT. Static mobile IPs exist only on some business plans.
A fixed US or Vietnam IP without changing your internet plan
Static ISP proxies hold one single-tenant address for the whole rental, with username and password login and renewal that keeps the same IP.
See static ISP proxies