A reservation is a CIDR block you set aside ahead of time. Later, you (or your Terraform pipeline) allocate non-overlapping child ranges from it. Reservations are the foundation of the Terraform provider and allocation API.
Create a reservation
- In the left sidebar, open Settings, then click the Reservations tab.
- Click New reservation.
- Fill in:
- CIDR (required) — e.g.
10.32.0.0/12. - Name (required) — e.g.
EU Production Block. - Description (optional) — owning team, ticket number, etc.
- Pool ID (optional) — paste an existing pool's UUID to associate the reservation with it.
- CIDR (required) — e.g.
- Click Create.
On Static CIDRs you can pick Kind → Future reservation in the Add dialog. It creates the same object and shows a "View Reservations →" link. Note this shortcut only keeps the CIDR and Label (which becomes the reservation's name) — it does not carry an owner note, expiry, or description, and it auto-resolves the pool. For full control, use the canonical path above.
Static CIDR vs future reservation
They look similar but do different jobs:
| Static (on-prem) CIDR | Future reservation | |
|---|---|---|
| What it is | A range you already use outside the cloud, declared for overlap detection. | A block held for the future that you carve allocations from. |
| Managed on | Static CIDRs page | Settings → Reservations |
| Plan | Starter+ | Pro+ |
| Purpose | Conflict awareness | Transactional IP allocation |
How reservations behave
- Overlaps are blocked at creation, not surfaced on the Conflicts page. You can't create a reservation that overlaps another reservation, equals an on-prem static, or contains one.
- An on-prem static that sits inside a reservation is an exclusion zone — the allocator carves around it.
- Reservations are IPv4-only today.
Allocating from a reservation
Once a reservation exists, request a right-sized child CIDR and VNet IQ hands back a non-overlapping range — transactionally. The fastest path is the Terraform provider or the REST allocation API, which is exactly what the next guide covers.