A static IP address is an Internet Protocol (IP) address that is assigned to a device or connection and stays the same over time. In a business context it usually means a fixed public address, or a block of addresses, assigned by the internet provider to your connection. Because it does not change, other systems can reliably find and trust it, which is why static addresses are used for VPNs, remote access, hosted services and allowlists.
At a glance
- A static address stays the same; a dynamic address can change when equipment restarts or a lease expires.
- Business internet services often include or offer static addresses, usually as a small block, for IPv4 and often IPv6.
- They are needed when others must reach your site at a known address or recognize your traffic by address.
- Provider-assigned addresses normally stay with the provider if you switch services.
- Some broadband services place customers behind carrier-grade NAT, which rules out static public addresses unless the provider offers them separately.
What problem it solves
Many systems identify a site by its IP address. A branch firewall builds a VPN tunnel to the head office’s address. A SaaS platform or partner allows logins only from your office’s address. Staff connect remotely to on-site systems. A camera system or server must be reachable from outside. If the public address changes, all of these break until someone updates the configuration.
A static IP address removes that problem: the address is fixed for as long as you keep the service, so configurations, DNS records and allowlists keep working.
How it works
Assignment. With a dynamic address, the provider’s equipment hands your router an address from a pool, and it can change. With a static address, the provider reserves a specific address or block for your connection and routes it to you. Inside the office, devices usually use private addresses, and the firewall translates them to the public address.
Address blocks. Business services often provide a block rather than a single address, described in CIDR notation such as /30, /29 or /28. A /29 contains 8 IPv4 addresses in total and a /28 contains 16. How many you can actually assign to devices depends on the provider’s design: some reserve the network, broadcast and gateway addresses inside the block, while others route the whole block to you over a separate link subnet. Ask for the exact usable count before ordering. Larger IPv4 blocks are harder to get because the supply of IPv4 addresses has run out, and providers may ask you to justify them. IPv6 blocks are far larger and often available at no extra charge.
Carrier-grade NAT. To stretch scarce IPv4 addresses, some broadband and cellular providers share one public address among many customers using carrier-grade NAT (CGNAT). Customers behind it generally cannot receive unsolicited inbound connections and do not have a public address of their own; a static address, where available, is usually a separate option.
DNS. Pointing a name such as vpn.example.com at a static address in the Domain Name System (DNS) gives users and systems a stable name to connect to.
Ownership. Provider-assigned addresses belong to the provider. Organizations that need addresses they can move between providers obtain their own address space and announce it using BGP.
Static addresses are standard with most dedicated internet access services and an add-on with many broadband plans. Our IPv4/IPv6 addresses page covers acquiring and managing larger blocks.
When it matters for buyers
- Ordering internet for a new site. Decide how many static addresses you need before ordering, and confirm the service supports them.
- Setting up VPNs or remote access. Fixed addresses at each end simplify configuration and troubleshooting.
- Meeting allowlisting requirements. Partners, banks and SaaS platforms may require a fixed source address.
- Changing providers. Plan for new addresses and update every system that refers to the old ones.
- Hosting services on site. Mail, web, camera or phone systems that must be reachable from outside need a public, stable address.
Questions to ask vendors
- Are static IP addresses included, and how many usable IPv4 addresses come with each block size?
- Is IPv6 available, and what size block do you assign?
- Is this service behind carrier-grade NAT? If so, can we get a public static address?
- What does each additional block cost, and what justification do you require?
- How long do changes to our address assignment take?
- Can we run BGP to announce our own address space instead?
How it differs from a dynamic IP address
A dynamic IP address is assigned automatically from a provider’s pool and can change, for example after an equipment restart, a lease expiry or network maintenance. Many residential and small business plans use dynamic addresses by default because they are simpler for the provider and sufficient for browsing and cloud apps. A static address is reserved for you and does not change while the service lasts. Some dynamic addresses stay the same for long periods in practice, but without a static assignment there is no commitment, so anything that depends on the address can break without warning.