--- title: IPAM - Concepts description: Learn about IP Address Management (IPAM) concepts with Scaleway. Understand how to organize, allocate, and manage IP resources efficiently in your cloud infrastructure. tags: ipam ip-address-management internet-protocol private-ip public-ip flexible-ip list-ips book-ip dates: validation: 2025-06-11 --- ## CIDR notation When viewing a private IP address in IPAM, it is shown in [CIDR notation](https://en.wikipedia.org/wiki/Classless_Inter-Domain_Routing#CIDR_notation). For example, the address `172.16.12.2/22` represents the IPv4 address `172.16.12.2` and its associated CIDR block `172.16.12.0/22`, defined on the [Private Network](/vpc/how-to/create-private-network/#how-to-configure-cidr) and containing 1024 addresses. ## IPAM IP Address Manager (IPAM) is the Scaleway tool for planning, tracking, and managing the IP address space of Scaleway products. It acts as a single source of truth for the IP addresses of Scaleway resources. Managed products, such as Databases and Load Balancer, are fully integrated into IPAM, and the [DHCP server](/vpc/concepts/#dhcp) of Private Networks uses IPAM to assign private, static IP addresses to attached resources. The public rollout of IPAM functionality is being carried out gradually. IPAM is now in General Availability, offering several different functionalities in the [Scaleway console](https://console.scaleway.com/ipam/), including viewing, tagging, and filtering all your [private IP addresses](#private-ip-address). You can also [reserve](/ipam/how-to/reserve-ip/) a private IP on one of your Private Networks and use it to attach an Instance, Load Balancer, Public Gateway, or Elastic Metal server to the network. More functionality is planned for the future, including: - Support for attaching Managed Databases and other resources to a Private Network using a reserved IP address - Management of public (flexible) IP addresses ## IPv4 Internet Protocol Version 4 (IPv4) is the standard protocol used for IP addresses, and routes most internet traffic as of today. Each IPv4 address has 32 bits. Written in human-readable form, an IPv4 address is generally shown as four octets separated by periods, e.g., `151.115.59.87`. Scaleway resources may have a [public](#public-flexible-ip-address) IPv4 address (flexible IP) for accessibility from the public internet, and will have a [private](#private-ip-address) IPv4 address for each Private Network they are attached to. ## IPv6 Internet Protocol Version 6 (IPv6) is the most recent version of the IP protocol used for IP addresses. Each IPv6 address has 128 bits. Written in human-readable form, an IPv6 address can be shown as eight groups of four hexadecimal digits, each group representing 16 bits and separated by a colon, e.g., `2001:0DB8:0000:0003:0000:01FF:0000:002E`. This can also be notated as `2001:DB8::3:0:1FF:0:2E`. IPv6-compatible Scaleway resources may have a [public](#public-flexible-ip-address) IPv6 address (flexible IP) for accessibility from the public internet, and will have a [private](#private-ip-address) IPv6 address for each Private Network they are attached to. For more details, see [IPv6 and the Scaleway ecosystem](/ipam/reference-content/ipv6/). ## Private IP address Private IP addresses identify devices on Private Networks. They are not routed on the public internet, and can be used to route traffic privately between resources attached to the Private Network, as well as to [other Private Networks in the same VPC](/vpc/concepts/#routing). When you attach a resource to a Private Network, you can either: - Specify a [reserved IP address](/ipam/how-to/reserve-ip/) to use for the attachment, or - Let the [DHCP](/vpc/concepts/#dhcp) of the Private Network assign it a private [IPv4](#ipv4) address from the Private Network [CIDR](/vpc/concepts/#cidr-block) block. In both cases, the private IP address of the resource will not change unless you detach the resource from the Private Network, or delete the resource. [IPv6](#ipv6) addresses can also be assigned for IPv6-compatible resources. Four IP addresses from each CIDR block are unavailable for reservation/use: the first two and last two in the block. For example, for the subnet `172.16.12.0/22` the following addresses cannot be reserved or assigned to any resource: `172.16.12.0`, `172.16.12.1`, `172.16.15.254` and `172.16.15.255`. ## Public (flexible) IP address Public IP addresses identify devices on the public internet. You can enter the public IP address of an Instance into any browser connected to the Internet, and access content being served from that Instance. Depending on the type of resource and its configuration, it may or may not have a public IP address. For example, you can choose to give an [Instance](/instances/) one or more public IP addresses ([IPv4](#ipv4) and/or IPv6), or alternatively, no public IP address at all. To find out more about managing public connectivity, see the [public connectivity best practices](/ipam/reference-content/public-connectivity-best-practices/). Public IP addresses at Scaleway are often called flexible IP addresses, because you can move them between different resources. However, flexible IP addresses are scoped to a single product and to a single Availability Zone. If you create a flexible IP address for an Instance in `PAR-2`, you can move it to a different Instance in `PAR-2`, but not to an Instance in `PAR-1`, nor to an Elastic Metal server in any AZ. ## Reserved IP address A reserved IP address is a private IP address from the [CIDR block](/vpc/concepts/#cidr-block) of a given Private Network, that you have [reserved via IPAM](/ipam/how-to/reserve-ip/). Reserving an IP means that it can no longer be auto-allocated by DHCP to resources that join the network. You can then use the reserved IP to attach a specified resource of your choice to the Private Network. After you detach the resource, the IP remains reserved, and you can either use it to attach a different resource, or release it back into the pool of generally available IPs.