Legacy IPv4 space: what the label means, and what it changes for a buyer
A block comes up for sale marked legacy, and the word does two jobs at once: it sounds like provenance, and it hides a paperwork question that decides whether you can get ROAs, what you will pay the registry each year, and whether the label survives the sale at all. Legacy is a registry status, not a class of address. Here is what it means at each registry as of August 2026, what it changes, and what to check before you sign.
What legacy means, registry by registry
Legacy space was issued before the regional registries existed, or outside their system. ARIN's definition is the most precise: an IPv4 block or AS number issued to the current registrant by InterNIC or its predecessors before ARIN's inception on 22 December 1997, and not brought under an ARIN agreement. RIPE NCC's policy speaks of resources obtained prior to or otherwise outside the current hierarchical distribution through the RIRs; APNIC calls it historical, a label that also takes in its own early delegations made before membership agreements; LACNIC's policy manual uses legacy too. When ARIN inherited the InterNIC-era records, the Early Registration Transfer project moved the ones belonging to other regions to their own registries between 2002 and 2005, which is why 130.89.0.0/16, a Dutch university's block, lives in the RIPE Database with status LEGACY while IANA's registry still lists its /8 as administered by ARIN. Scale is hard to state honestly. IANA marks 92 of the 256 /8 rows LEGACY, and RIPE Labs estimated in January 2024 that legacy space is roughly 36 percent of the IPv4 internet, but the /8 rows include space long since transferred and re-registered under agreements: 3.0.0.0/8 is a LEGACY row at IANA and is registered to Amazon in its entirety today, while 19.0.0.0/8 is still an intact legacy /8 outside any ARIN agreement.
What it changes: paperwork, RPKI and fees
The label changes what the registry will do for you without a contract, and what a contract costs. At ARIN, legacy holders without an agreement still get WHOIS and RDAP updates and reverse DNS delegation, but must be under an ARIN agreement to access RPKI and the IRR: no agreement, no ROAs, no route objects at ARIN. From October 2007 to the end of 2023 ARIN offered a Legacy Registration Services Agreement with a capped fee; since 1 January 2024 legacy space brought under agreement signs the standard RSA and pays regular fees, from US$275 a year for a /24 or smaller under the schedule effective 1 January 2026, while pre-2024 signers keep a cap of US$250 for 2026 rising by US$25 a year. In the RIPE region, the legacy policy (ripe-639, current text from March 2015, first adopted in 2014) offers four contractual routes (registering under your own LIR, membership, a sponsoring LIR, or a direct agreement), and if you choose none the RIPE NCC keeps providing existing registry services but is not obliged to start new ones; its services matrix shows route object maintenance available even without a formal relationship and RPKI certification withheld, because certificates depend on a contractual relationship. Under the 2026 charging scheme a direct agreement costs the same as an LIR account, EUR 1,800 a year, and legacy space held through a sponsoring LIR is EUR 75 per resource. Both registries have already adopted 2027 schedules, so re-check every number here after 1 January 2027. APNIC requires an account, Member or non-member, before it updates a historical record, has offered RPKI to those account holders since March 2021, and removed unclaimed historical registrations from its WHOIS after 1 January 2023.
What happens when it is sold
Whether the label travels with the block depends on the registry, and this is where a buyer's premium logic lives or dies. At ARIN the recipient of a transfer must be under an RSA covering the block (signing one if it has none), and on an 8.3 or 8.4 sale the block stops being legacy the day it moves, though a recipient under an 8.2 merger or acquisition can opt to keep the legacy status; APNIC treats transferred historical resources as current resources under all its policies; LACNIC's manual says legacy resources transferred into its region are no longer legacy. Only the RIPE NCC currently lets a recipient keep LEGACY status on a transfer within its region, handling those transfers on a best-effort basis because, as the RIPE NCC puts it, no RIPE policy specifically covers them, and a pre-proposal in October 2025 sought to end that inheritance, so check the proposals page before you pay for it. Two well-known sales show the ARIN side. MIT announced in 2017 that it would sell about eight million addresses from 18.0.0.0/8; ARIN's registry today shows 18.32.0.0 through 18.255.255.255 registered to Amazon and MIT retaining 18.0.0.0/11, which ARIN's daily agreement report lists under Basic Legacy Services rather than Full Registry Services. ARDC sold 44.192.0.0/10, the upper quarter of the amateur radio block, in July 2019, and 44.0.0.0 through 44.191.255.255 remains registered to ARDC with a 1992 date. Some brokers advertise a premium of five to twenty percent for legacy space in the RIPE region; that is a marketing claim with no independent price series behind it, and it applies only where the status survives the sale.
The buyer's checks
For an ARIN block, ARIN publishes a daily Resources Under RSA report that labels every network and AS record either Full Registry Services or Basic Legacy Services; that is your first check, followed by the transfer log to see whether the block has moved before, and by asking the seller which agreement covers it, since an organisation ID ending in -Z signals a pre-2024 LRSA but proves nothing about this block. In the RIPE Database, status LEGACY on the inetnum tells you the space is legacy but not whether a contract exists; a sponsoring-org attribute or the RIPE-NCC-LEGACY-MNT maintainer is an indicator to follow up, and the seller should be able to name the arrangement. For APNIC historical space, confirm the record still exists and has an account holder, because unclaimed records have been removed. Then read the block's history the way you would any other block: legacy is not a certificate of good behaviour, and a /16 issued in 1993 has had thirty years to be leased, announced by strangers, and listed.
What it does not change
Legacy has no meaning to a router. Route origin validation treats a legacy prefix exactly like any other, blocklists do not know the word, and reputation systems read what the addresses did, not when they were issued. What the label changes is entirely on the registry side: which paperwork you must sign to get ROAs and route objects, what you pay, and whether the status outlives the sale. Settle those with the registry and the seller; settle the block's past with its history.
Look up the block on the front page for the dates the registry publishes, which on ARIN legacy records predate ARIN itself: the allocation and registration dates, which registry's published holdings the space appears in and from when, every network that has announced it with first and last seen dates, and the abuse contact as published. A legacy block that sat unannounced for years and was revived reads very differently from one registered in 1993 and announced without a break for as long as the routing record reaches, and the difference is in the timeline.