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4.3. Hierarchical Allocation

4.3. Hierarchical Allocation​

With Hierarchical Allocation, delegated administrators are given control over part of the namespace and can assign values in that part of the namespace. IANA makes allocations in the higher levels of the namespace according to one of the other policies.

Examples:

  • DNS names - IANA manages the top-level domains (TLDs), and, as [RFC1591] says:

    Under each TLD may be created a hierarchy of names. Generally, under the generic TLDs the structure is very flat. That is, many organizations are registered directly under the TLD, and any further structure is up to the individual organizations.

  • Object Identifiers - defined by ITU-T recommendation X.208. According to http://www.alvestrand.no/objectid/, some registries include

    • IANA, which hands out OIDs under the "Private Enterprises" branch,
    • ANSI, which hands out OIDs under the "US Organizations" branch, and
    • BSI, which hands out OIDs under the "UK Organizations" branch.

  • URN namespaces - IANA registers URN Namespace IDs (NIDs [RFC8141]), and the organization registering an NID is responsible for allocations of URNs within that namespace.

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