Summary

  • ARIN records 911 Windstream Communications LLC-to-EarthLink M&A transfer rows on 11–12 February 2021, containing 485,632 nonoverlapping IPv4 addresses. On 18 April 2023, 411 M&A rows moved 228,352 addresses in the other direction; every address in that later group lies within the earlier one.
  • The 2023 group covers 47.0% of the 2021 address set. A 2021 transfer of 24.235.64.0/20 shows the split in miniature: its upper /21 returned to Windstream in 2023 and moved to Amazon in 2024, while current ARIN RDAP still names EarthLink for the lower /21.

A registry can make a round trip look wonderfully tidy. In February 2021, ARIN placed 911 Windstream Communications LLC-to-EarthLink rows in its transfer ledger. In April 2023, it stamped 411 rows EarthLink-to-Windstream. The temptation is to draw a fat arrow right, a thinner arrow left, and call it a reversal. The addresses tell a sharper story: all 228,352 IPv4 addresses in the second arrow came from the first, but 257,280 in the first did not come back in that 2023 batch.

The two February timestamps matter. Fifty entries share 11 February 2021 at 21:06:48 UTC; 861 share 12 February at 22:04:47. All 911 are classified MERGER_ACQUISITION, all run ARIN-to-ARIN, and their transfer sets contain one IPv4 interval each. Converting ARIN's zero-padded addresses to ordinary IPv4 numbers and merging adjacent intervals gives 485,632 unique addresses, with no overlap among the 911 rows. The first day's 50 rows account for 12,800 addresses; the next day's 861 account for 472,832. A row is a record unit, not a standard-sized parcel.

On 18 April 2023 at 14:15:50 UTC, the ledger puts 411 EarthLink-to-Windstream M&A rows under one second. They contain 228,352 unique IPv4 addresses and no IPv6 block or ASN. An exact interval intersection, not a company-name guess, puts every one of those addresses inside the 2021 Windstream-to-EarthLink set. The reverse group is 47.02% of the earlier addresses. It includes all 12,800 from 11 February and 215,552 from 12 February. The unmatched 257,280 are simply outside this particular 2023 reverse group; some have other later transfer receipts.

One /20 supplies the diagram the aggregate cannot. The 24.235.64.0–24.235.79.255 interval entered ARIN's log in September 2018 as Earthlink, Inc. to Windstream. The 2018 label and the later EarthLink label have different spelling and are kept as different recorded names. In February 2021, Windstream transferred that exact 4,096-address /20 to EarthLink. In April 2023, EarthLink transferred only 24.235.72.0–24.235.79.255, the upper 2,048-address /21, to Windstream. In March 2024, Windstream transferred precisely that upper half to Amazon.com, Inc. The bottom half has no matching row in those two later movements.

Today's two ARIN RDAP answers preserve the split. The lower 24.235.64.0/21 object names EarthLink as registrant. The upper 24.235.72.0/21 object names Amazon.com, Inc. Both replies are for exact 2,048-address halves. A query for the old /20 instead falls back to the much wider ARIN parent, so the two explicit /21 queries are the useful comparison. The lower object's last-changed timestamp is 18 April 2023 at 10:15:32 Eastern time, seconds before the reverse cohort's UTC transfer stamp; the upper object's registration and last-change are 26 March 2024.

The present database is a set of children, while the historical ledger still holds the full /20 receipt.

Another part of the 2021 batch travelled in a different direction. ARIN shows 24.40.128.0/18 going EarthLink-to-1&1 Versatel Deutschland GmbH and ARIN-to-RIPE NCC on 22 March 2022. RIPE's current exact RDAP reply names 1&1 Versatel GmbH. That /18 was never in the 2023 EarthLink-to-Windstream set. It would be false arithmetic to call every 2021 address outside the reverse group an EarthLink address today. The transfer ledger gives event edges; current RDAP gives selected present registrations.

The institutional question is where the reader is asked to stop. A single transfer page can show two company names and a date; it cannot display what happened to a whole prior cohort after one part returns, another crosses a registry border, and a half-block moves again. ARIN has published enough to reconstruct those paths, but the reader has to normalize addresses, join exact bounds, and re-query the resulting children. The ledger has no transaction price or migration schedule. A dated agreement and a route cutover record would explain commercial and operational changes; neither sits in these registry rows.

The reward for following the intervals is a less comforting but more useful answer. The 2023 reverse batch was wholly drawn from the 2021 batch, yet the 2021 batch did not reverse as a whole. At 24.235.64.0/20, a neat corporate arrow becomes two live /21s with different registrants. The registry did its bookkeeping; the old rectangle did not promise to stay rectangular.

RIR originals