DigitalOcean Reserved IPs are publicly-accessible static IPv4 addresses. Assign and reassign reserved IP addresses to Droplets as needed, or implement an automated failover mechanism with reserved IPs to build a high availability infrastructure. IPv6 support is now available in public preview. Enroll in the feature preview to create reserved IPv6 addresses.
Reserved IPs let you redirect network traffic between any of your Droplets within the same datacenter. Assigning a reserved IP to a Droplet doesn’t replace or change its original public IP address.
You can use reserved IPs to create server infrastructures without single points of failure, but a reserved IP alone does not automatically provide high availability. For a setup to be highly available, you need to implement a failover mechanism to automate the process of detecting failures of the active server and reassigning the reserved IP to a passive server.
For example, you can assign a reserved IP to a Droplet that is running a web application. You can then write a script that uses the DigitalOcean Monitoring API to monitor the Droplet’s performance and then reassign the IP address to a backup Droplet (using the API) if the original Droplet’s performance becomes unstable or poor.