The two lifecycles
The simplest way to remember it: auto-assigned = the VM owns it, reserved = your account owns it.
Why two lifecycles exist
Cloud providers used to give every VM “a public IP” and called it a day. The problem is that two very different needs were sharing one mechanism:- The “I just want this VM on the internet” need — short-lived, replaceable, no commitment. Free is good. Whatever IP you got is fine.
- The “I have published this IP somewhere I can’t easily change” need — DNS records, customer firewalls, certificate-pinned clients, partner whitelists. The address is a contract. It can’t change without coordinated work.
- Charging for everything so the addresses survive (everyone pays even though most don’t care), or
- Releasing on detach so the free path works (and breaking everyone who cared about stability)
The lifecycle, picture by picture
Auto-assigned
Detaching is terminal — the IP doesn’t come back to your account. If you re-add a public IP to the same VM later, you get a different address.Reserved
The IP stays yours through every state except after Release. Billing runs continuously through every state except after Release.When to pick which
Rule of thumb: if you’d write a runbook step that says “update DNS record” when the IP changes, you should be on a reserved IP and not have that step at all.
Cost framing
A reserved IP costs $3/month — $36/year. That’s roughly equivalent to:- One hour of a small VM
- One terabyte-month of object storage above the free tier
- Half a tank of coffee at most cafés
What’s the same regardless of type
Both auto-assigned and reserved IPs share these properties:- IPv4 and IPv6 are both supported (one of each per VM from the dashboard; more via support)
- Both are routable on the public internet — same upstream, same MTU, same gateway
- Both can have a Firewall attached to filter inbound traffic (see Firewall when written)
- Both bill the same way — continuous accrual, settled month-end on the 1st (auto-assigned just bills at $0)
- Both are region-locked — an IP allocated in
us-eastcan only attach tous-eastVMs - Both count toward the same per-VM cap — one IPv4 and one IPv6 per VM from the dashboard
What about Gateway IPs?
A third category exists in the Public IPs list — gateway IPs that belong to a VPC’s Internet Gateway. These are taggedGateway and aren’t directly assignable to VMs:
- They’re allocated automatically when you Enable a Platform Router (free, returned on Disable) or Deploy a Firewall Appliance (rolled into the appliance VM’s price)
- They can’t be moved by hand, reserved, or released through the Public IPs tab — they’re tied to their gateway’s lifecycle
- They appear in the Public IPs list for visibility, not for direct management
Related
Auto-assign a public IP
Free pool IP for non-stable addresses.
Reserve a static IP
Hold an IP across VM rebuilds for $3/mo.
Features & limits
Concrete numbers — pricing, regional pools, caps.