  Allocation of the global IP address space is under the purview of IANA, who
distributes management responsibility among five geographically distinct
Regional Internet Registries (RIRs). Each RIR is empowered to bridge technical
(e.g., address uniqueness and aggregatability) and policy (e.g., contact
information and IP scarcity) requirements unique to their region. While
different RIRs have different policies for out-of-region address use, little
prior systematic analysis has studied where addresses are used post-allocation.
  In this preliminary work, we e IPv4 prefix registrations across the five RIRs
(50k total prefixes) and utilize the Atlas distributed active measurement
infrastructure to geolocate prefixes at RIR-region granularity. We define a
taxonomy of registration ``geo-consistency'' by comparing a prefixes' inferred
physical location to the allocating RIR's coverage region as well as the
registered organization's location. We then apply this methodology and taxonomy
to audit the geo-consistency of 10k random IPv4 prefix allocations within each
RIR (50k total prefixes). While we find registry information to largely be
consistent with our geolocation inferences, we show that some RIRs have a
non-trivial fraction of prefixes that are used both outside of the RIR's region
and outside of the registered organization's region. A better understanding of
such discrepancies can increase transparency for the community and inform
ongoing discussions over in-region address use and policy.

Networking and Internet Architecture