Summary

  • ARIN defines allocation, reallocation and reassignment by where a block sits in the registration chain and whether the recipient intends to distribute addresses further or use them internally.
  • Net Type is therefore evidence about a registered delegation path. It does not, by itself, prove a continuing customer-provider contract, present operational control, BGP origination or reachability.

A compact label for a registration decision

ARIN’s Whois guidance presents Net Type as a field on a network record. Its reassignment guidance supplies the distinctions behind the label. When ARIN issues a block to a customer that plans to distribute pieces to its own customers, the record is an allocation. A downstream block is a reallocation when its recipient intends to distribute addresses again. It is a reassignment when the recipient intends to use the addresses internally.

Those definitions encode a branch in a registry workflow. They help explain why one record appears beneath another and what kind of downstream registration was reported. They do not say that the commercial arrangement observed or assumed when the record was created still exists today. Nor do they describe every contract, service or routing dependency between the parties.

The distinction matters because the labels sound more current than the evidence. “Reallocated” can be read as “this organisation currently buys transit from the parent”. “Reassigned” can be read as “this organisation operates every address in the range”. Neither conclusion follows from the field definition. The record tells us how the block was registered; a present relationship requires present evidence.

Intent is not topology

The allocation/reallocation divide is based on intended downstream distribution. That is an administrative purpose, not a map of packet movement. A recipient may use several transit providers, announce through different autonomous systems, outsource infrastructure, keep the range dormant or alter its network design without changing the historical reason the record was created.

Likewise, a reassignment’s “internal use” classification does not identify the routers, sites, services or people using each address. It does not establish that the assignee holds credentials today or that the upstream registrant is still its supplier. The registry class and the operational arrangement can be related, but they are not interchangeable evidence.

A live ARIN RDAP response exposes a time-bounded registration object: range, handle, parent, related entities, events and registry-specific metadata. It does not observe BGP. To say which ASN originates a prefix now, where the route is visible or whether traffic reaches a service, an analyst needs time-aligned routing and data-plane observations. To say who contracts with whom, the analyst needs current commercial or directly confirmed evidence.

Hierarchy still matters

Rejecting the customer-map shortcut does not make Net Type useless. ARIN states that reallocations and reassignments may only be made from an allocation. The type therefore helps reconstruct the registered delegation chain. It can guide an investigator toward the upstream registration, the downstream entity and the reporting path that created the record.

ARIN also requires qualifying IPv4 and IPv6 subdelegations to be reported within a specified period. That rule explains why the registry is an accountability surface. It does not guarantee that every later operational or commercial change appears immediately in the same field. A capture should preserve the query, retrieval time, handle, parent, type, range, entities and event dates so that a later reader can distinguish the observed record from an analyst’s interpretation.

Deletion rules reinforce the time boundary. ARIN documents that a reassigned or reallocated NET can be removed and that downstream records can be affected. A record present on one date is evidence of the registry state on that date. Its later deletion does not make the earlier capture false; its earlier presence does not make the relationship permanent.

Ask the next question in the right system

Net Type can answer: how did ARIN classify this registered block in the delegation chain? It cannot finish questions about present connectivity, authority or ownership. Each of those needs a separate test.

For routing, capture BGP observations with time and vantage point, then distinguish observed origin from RPKI authorization and IRR declarations. For operational control, seek current operator confirmation, change records or other evidence tied to the systems in question. For a commercial relationship, use current contracts, invoices, public disclosures or confirmation from the parties. For legal ownership, use the relevant agreements and law rather than promoting a registry label into a title instrument.

The disciplined reading is modest but useful: Net Type records registration path and declared distribution purpose. Preserve it as such. Then let current evidence—not the familiarity of the label—carry current claims.

Sources