Floating IPs

Updated 2026-10-30

A Wolkra floating IP is a public IP address that you can move from one server to another in seconds, so your service keeps the same address while the machine behind it changes. It is the simplest building block for failover and zero-downtime server swaps in Frankfurt.

Why a floating IP helps

A server's primary IP is tied to that server. When you replace the server, the address goes with it, and you have to update DNS and wait for caches to expire. A floating IP breaks that link: the address belongs to your project, and you decide which server it points to.

• Failover: if the active server fails, move the address to a standby server.
• Server swaps: build a new server, test it, then move the address. Visitors never see a DNS change.
• Maintenance: shift traffic away from a server you need to patch or resize.
• Stable allow-lists: partners who allow your address keep working when you replace hardware.

How it works

1. Create a floating IP in your project.
2. Assign it to a server. Wolkra routes traffic for that address to the server.
3. Configure the address on the server's network interface so the operating system accepts it.
4. When you want to move it, reassign it to another server. Routing switches in seconds.

Because step 3 lives inside your servers, prepare the configuration on every server that might take over. Many teams use cloud-init user data so new servers come up with it already in place.

In the console and the API

In the console, floating IPs have their own list. Assign, unassign and move them with a click, and set a reverse DNS (PTR) name for each one.

For automatic failover, use the Wolkra API. A small health-check script or a tool such as keepalived running on your servers can call the API to reassign the address when the active node stops answering. Create a project-scoped token with read/write access, limit it to your servers' addresses with the optional IP allow list, and keep it on the servers that need it. See API tokens.

Floating IP or load balancer?

Many setups use both: a load balancer for web traffic and a floating IP for a database primary or a mail or VPN server.

Typical uses

• An active/standby pair for a VPN server
• A stable address for a game server you rebuild often
• A primary database address that moves to the replica on failover
• Blue/green releases for web hosting

Planning a failover pair

A simple active/standby setup with a floating IP looks like this:

1. Create two servers with the same software and data replication between them.
2. Put both in a placement group so they run on different hosts.
3. Configure the floating IP on the network interface of both servers.
4. Assign the floating IP to the active server and point DNS at it.
5. Run a health check on the standby. When the active server stops answering, the standby calls the API and takes over the address.

Test the switch before you need it. Move the address by hand once, check that clients reconnect and that the standby serves traffic correctly, then move it back. A failover that has never been tried is only a plan.

Pricing basis

Floating IPs are charged per started hour from your prepaid balance and capped at the monthly price. Traffic to and from them is unmetered, like all Wolkra traffic. See the pricing page.

Limits to know

• A floating IP points to one server at a time.
• It can move between servers in the same location. Today that is Frankfurt.
• The operating system must be configured to accept the address.
• To spread servers across hosts, so a standby does not share the active server's host, use a placement group.

Related products

• IP addresses: IPv4, IPv6, reverse DNS and Elastic IPs
• Load balancers
• Placement groups
• Network

Keep your address when servers change

Swap, patch and fail over without touching DNS. Sign up for Wolkra and create a floating IP in Frankfurt.