Using a DigitalOcean Reserved IP to switch servers without waiting on DNS

What a reserved IP changes about a server swap

A Droplet's own public IP belongs to that Droplet. If you rebuild on a new Droplet, the new one gets a different address, so you update the A record and wait for resolvers to drop the old answer. On a course site that wait is awkward: some students reach the new server while others still reach the old one, and anything they do on the old server, such as completing a lesson, submitting a quiz or buying a course, lands in a database you are about to throw away.

DigitalOcean describes reserved IPs as publicly accessible static IPv4 and IPv6 addresses that can be reassigned to a different Droplet in the same datacenter, or unassigned entirely. If DNS points at the reserved IP rather than a Droplet's own address, the DNS record never changes during a swap. You move the address from the old Droplet to the new one, and the change is made inside DigitalOcean's network rather than in thousands of resolver caches.

DigitalOcean's reassignment documentation does not say how long a reassignment takes to take effect or whether open connections are dropped. Time it yourself in a rehearsal with two test Droplets before relying on it for a launch-week change.

Pricing and limits at a glance

These are the published terms from DigitalOcean's pricing and limits pages. The most important line for budgeting is the difference between an assigned and a parked IPv4 address.

Inbound and outbound: the part that surprises people

A reserved IP is mainly about inbound traffic. By default, DigitalOcean says a Droplet's outbound IPv4 traffic still leaves from the Droplet's own public address. That matters if a payment gateway, licence server, SMTP relay or firewall allowlists your server's IP: after a swap, outbound requests come from the new Droplet's own address, not the reserved IP, and the allowlist entry no longer matches.

You can make outbound IPv4 traffic leave from the reserved IP by routing it through the Droplet's anchor gateway. DigitalOcean's steps are to fetch the anchor gateway from the metadata service, replace the default route with ip route, and then make the change persistent in the network configuration for your distribution, disabling cloud-init's network configuration so it does not overwrite your change. An ip route change alone is lost on reboot. For IPv6, outbound traffic uses the reserved IPv6 automatically only when the Droplet has no static IPv6 address.

Do not route mail through the reserved IP. DigitalOcean's limits page says SMTP ports 25, 465 and 587 are blocked on reserved IPs. Course sites usually send password resets, receipts and enrollment emails, so send them through a transactional email provider and keep that path independent of which Droplet holds the address.

One-time setup: moving DNS onto the reserved IP

The first change is an ordinary DNS migration, so plan it like one. Create the reserved IP in the same datacenter region as the current Droplet and assign it there. With doctl, a reserved IPv4 is created and assigned in one step: doctl compute reserved-ip create --region REGION --droplet-id DROPLET_ID. DigitalOcean notes this create command requires a Droplet at creation. A reserved IPv6 is created with doctl compute reserved-ipv6 create --region REGION, and every Droplet needs manual configuration after a reserved IPv6 is assigned.

Before you touch DNS, check that the site answers on the reserved IP, for example with curl using --resolve to send your real hostname to the new address. Then lower the TTL on the A record ahead of time, change the record to the reserved IP, and wait out the old TTL once. From then on, every server swap is a reassignment, not a DNS change.

Keep the address assigned. A reserved IPv4 that sits unassigned for a 72-hour rebuild accrues $0.72 at the hourly rate; left parked for a whole month it costs $5. If you are between servers, leave it on the old Droplet until the new one is ready.

Server-swap runbook for a course or membership site

• Build the replacement Droplet in the same datacenter as the reserved IP. A reserved IP cannot move between datacenters, so a region change still needs DNS.
• Install and configure the stack, restore files and the database, and test the new Droplet on its own IP with curl --resolve or a hosts-file entry.
• If the new Droplet must send outbound traffic from the reserved IP, configure the anchor gateway route and its persistent network file now, and reboot to prove it survives.
• Put the old site in maintenance mode or otherwise stop writes, so no enrollments, quiz attempts or orders land on the old database after your final copy.
• Take the final database export from the old Droplet and import it on the new one.
• Reassign the address: doctl compute reserved-ip-action assign RESERVED_IP NEW_DROPLET_ID, or Networking, Reserved IPs, Reassign in the control panel.
• Check from outside: load the login page, a lesson and checkout; confirm the response comes from the new server, for example with a header or a build marker you added.
• Leave the old Droplet running and untouched until you are satisfied. Rollback is the same command pointed at the old Droplet ID.
• Destroy or snapshot the old Droplet only after the new one has handled renewals, scheduled jobs and email for a full billing cycle you care about.

Who it fits and who should skip it

It fits a self-managed WordPress or LMS site on DigitalOcean Droplets where you expect to rebuild the server, change the OS version or resize by building fresh rather than in place. It also fits a simple active and standby pair in one datacenter, which DigitalOcean mentions as an automated failover use for reserved IPs, though the failover logic is yours to build.

Skip it if you are leaving DigitalOcean, moving to a different region, or moving to a managed host: the reserved IP cannot follow you, so you are back to a DNS change. It also adds little if you only ever resize the same Droplet in place, because the Droplet's own address does not change then. And if third parties allowlist your outbound IP, budget time for the anchor-gateway routing or for updating those allowlists on every swap.

Checklist

• Reserved IP created in the same datacenter as the Droplet, and assigned (not parked).
• DNS A record points at the reserved IP; AAAA points at a reserved IPv6 if you use IPv6.
• Outbound allowlists reviewed: either they list each Droplet's own IP, or outbound traffic is routed through the reserved IP and the route survives a reboot.
• Email sent through a provider, not through SMTP ports on the reserved IP.
• Reassignment rehearsed between two test Droplets and the switch-over time noted.
• Rollback command written down with the old Droplet ID before you start.
• Old Droplet kept until scheduled jobs, renewals and email have run on the new one.

Sources & verification

Product details and prices can change. Check the linked provider before buying.

1. DigitalOcean: Reserved IPs overview Accessed 30 Oct 2026
2. DigitalOcean: Reserved IPs pricing Accessed 30 Oct 2026
3. DigitalOcean: Reserved IPs limits Accessed 30 Oct 2026
4. DigitalOcean: Reassign or unassign reserved IPs Accessed 30 Oct 2026
5. DigitalOcean: Create reserved IPs Accessed 30 Oct 2026
6. DigitalOcean: Send outbound traffic over a reserved IP Accessed 30 Oct 2026