# Prefixes

A prefix is an IPv4 or IPv6 network and mask expressed in CIDR notation (e.g. 192.0.2.0/24). A prefix entails only the "network portion" of an IP address: All bits in the address not covered by the mask must be zero. (In other words, a prefix cannot be a specific IP address.) Prefixes are automatically organized by their parent [aggregate](./aggregate.md) and assigned [VRF](./vrf.md).

## Fields

### Prefix

The IPv4 or IPv6 network this prefix represents.

### Classification

Classification describes the address space covered by a prefix and is read-only. It does not indicate ownership, route advertisement, or reachability.

The most specific containing range determines the classification, and adjacent ranges of the same classification are treated as one. For example, `192.0.0.0/24` is special-purpose and `192.0.0.9/32` is public. Prefixes that do not fit another classification, such as `10.0.0.0/7`, are public.

| Classification  | Address space                                                                                             |
|-----------------|-----------------------------------------------------------------------------------------------------------|
| Public          | All other space, including globally reachable blocks such as 192.0.0.9/32 and 64:ff9b::/96                 |
| Private         | 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16 (RFC 1918), fc00::/7 (RFC 4193)                               |
| Shared          | 100.64.0.0/10 (RFC 6598)                                                                                  |
| Loopback        | 127.0.0.0/8, ::1/128                                                                                      |
| Link-local      | 169.254.0.0/16, fe80::/10                                                                                 |
| Documentation   | 192.0.2.0/24, 198.51.100.0/24, 203.0.113.0/24, 2001:db8::/32, 3fff::/20                                   |
| Multicast       | 224.0.0.0/4, ff00::/8                                                                                     |
| Benchmarking    | 198.18.0.0/15, 2001:2::/48                                                                                |
| Special-purpose | Other blocks of the IANA special-purpose registries which are not marked globally reachable (including deprecated blocks, TEREDO and 6to4), and IPv6 space reserved by the IETF |

!!! note
    Custom validators use `classification`, which reflects the current prefix. Object permission constraints and direct ORM queries use the stored copy, `_classification`.

### Status

The prefix's operational status. Note that the status of a prefix does _not_ have any impact on its member [IP addresses](./ipaddress.md), which may have their statuses defined independently. The "container" status indicates that the prefix exists merely as a container for organizing child prefixes.

!!! tip
    Additional statuses may be defined by setting `Prefix.status` under the [`FIELD_CHOICES`](../../configuration/data-validation.md#field_choices) configuration parameter.

### VRF

The [Virtual Routing and Forwarding](./vrf.md) instance in which this prefix exists.

!!! note
    VRF assignment is optional. Prefixes with no VRF assigned are considered to exist in the "global" table.

### Role

The user-defined functional [role](./role.md) assigned to the prefix.

### Is a Pool

Designates whether the prefix should be treated as a pool. If selected, the first and last IP addresses within the prefix (normally reserved as the network and broadcast addresses, respectively) will be considered usable. This option is ideal for documenting NAT pools.

### Mark Utilized

If selected, this prefix will report 100% utilization regardless of how many child objects have been defined within it.

### Scope

!!! info "This field replaced the `site` field in NetBox v4.2."

The [region](../dcim/region.md), [site](../dcim/site.md), [site group](../dcim/sitegroup.md) or [location](../dcim/location.md) to which the prefix is assigned (optional).

### VLAN

The [VLAN](./vlan.md) to which this prefix is assigned (optional). This mapping is helpful for associating IP space with layer two domains. A VLAN may have multiple prefixes assigned to it.