Summary

  • ARIN's newly posted data-accuracy slides say 2,768 legacy prefixes totaling 1.28 million /24 equivalents came under Registration Services Agreements in Q4 2025, the program's biggest quarter.
  • At Q3 2026, 372,877 /24 equivalents remained outside agreements; 715 /16 blocks held 49.1% of that remaining address volume.

ARIN's legacy-address file had a quarter that would make most spreadsheet charts look broken. In slides posted for ARIN 58, the registry says 2,768 legacy prefixes, amounting to 1.28 million /24 equivalents, came under Registration Services Agreements in the fourth quarter of 2025. It calls that the largest single-quarter change in the program's history, driven primarily by large legacy allocations. Its meeting recap repeated the figure on 23 October.

The number describes a contract and registry-status change. The address space was brought under agreement. ARIN's separate figure for address space distributed through the IPv4 Waiting List is 2,195 /24 equivalents at Q3 2026. Put those figures in different drawers: a holder signing a services agreement and a block being released to another applicant are different events. Mixing them would turn a registry cleanup into a fictional land rush.

By the third quarter of 2026, ARIN counted 372,877 /24 equivalents still outside agreement, an 81% decrease from Q1 2024. The Q4 2025 surge was more than three times that later stock in the same /24 unit. Yet the remaining work has serious mass. The slides say 715 /16 blocks account for 49.1% of the residual space, while just 23 blocks of /15 or larger account for about 38%. The bulk move did not make large-address holders disappear from the to-do list.

The next stage looks increasingly like casework. ARIN's program separates organizations whose holder data are unknown, holders with contact details to verify, and known holders whose resources lack an agreement. That is a different labor problem from processing one enormous agreement cohort. The public presentation does not identify which organizations or blocks produced the record quarter, or explain its internal sequence. What it does show is a sudden improvement in agreement coverage followed by a stubborn inventory with large blocks still at its center.

For members and observers, the useful follow-up is a series that keeps three counters separate: agreements signed, holder records verified, and space actually returned or redistributed. ARIN has now shown how much moved in a single quarter. The real test is whether the registry can show how the remaining rocks are dealt with, one holder at a time.