AS501

AS501 (AFCONC-BLOCK1-AS) is a legacy autonomous system number registered under ARIN to Air Force Systems Networking, a U.S. Department of Defense numbering resource administered on behalf of the Air Force by DISA-Columbus. The ARIN RDAP record for AS501 is represented as part of a block range spanning AS379 through AS508 under handle AS379, with the registrant entity 7ESG listing Maxwell AFB, Alabama as the organizational address and administrative/technical/abuse duties delegated to a DISA-Columbus contact entity in Whitehall, Ohio. The block's top-level registration event dates to 1989-08-04, with the record last changed 2008-06-06. AS501 is not a commercial network — it carries no PeeringDB record and no published peering policy, consistent with a closed government numbering resource rather than an ISP or content network. Multiple independent routing sources (RIPEstat, CAIDA, bgp.he.net, bgp.tools) agree AS501 announces zero prefixes as of 2026-07-10 and has been invisible in the global routing table since 2025-02-17. Its CAIDA AS rank of 79,459 and singleton customer cone reflect this dormancy. Notably, RIPEstat's routing-history data shows two brief, unexplained anomalies: an approximately 11-day window in February 2025 where AS501 originated 14 AFRINIC-registered /24 prefixes legitimately held by unrelated operators (including AS36920, KKON Technologies), and an earlier 2013 mismatch involving a LACNIC prefix legitimately held by AS10617. Neither episode is corroborated by Spamhaus, NANOG, or other secondary abuse-intelligence sources, so both are reported here as unconfirmed, dated routing observations rather than a verified hijack or abuse finding.

Operator

Air Force Systems Networking (US DoD/Air Force; ARIN OrgID 7ESG); admin/tech/abuse delegated to a DISA-Columbus contact entity [Confirmed] — ARIN RDAP autnum/501

Country / RIR

US, ARIN [Confirmed] — ARIN RDAP; RIPEstat abuse-contact-finder (authoritative_rir: arin)

Allocated

1989-08-04 (ARIN autnum TOP-LEVEL registration event, block range AS379–AS508, handle AS379); last changed 2008-06-06 [Confirmed] — ARIN RDAP autnum top-level events, corroborated by bgp.tools

Org status

active per ARIN registry status, though operationally dormant in BGP since February 2025 [Confirmed] — ARIN RDAP

Contacts

abuse/admin/tech via disa.columbus.ns.mbx.arin-registrations@mail.mil [Confirmed] — ARIN RDAP

Security/abuse context (NEUTRAL, DATED)

no notable public abuse signal found as of 2026-07-10 — absent from Spamhaus ASN-DROP and NANOG mailing-list archives

Network & routing

Network type

US DoD/Air Force internal government numbering resource; not a commercial ISP/CDN; no PeeringDB record found [Confirmed] — ARIN RDAP; peeringdb.com/api/net?asn=501 (404)

Routing status

dormant — 0 IPv4/IPv6 prefixes currently announced; not seen in the global table since 2025-02-17; 0/327 v4 and 0/321 v6 RIS peers seeing it [Confirmed] — RIPEstat routing-status, bgp.he.net, bgp.tools

Peering/upstreams

no upstreams or current peers observed; historical last-observed peer AS36920 (KKON Technologies Ltd) [Likely] — bgp.he.net/AS501

RPKI

not assessable — 0 prefixes currently announced, so no ROAs to validate [Unknown] — RIPEstat rpki-validation (skipped, requires a prefix)

Notable usage / routing anomaly

14 historical IPv4 prefixes total; two brief unexplained episodes — 2025-02-17 to ~2025-02-28 origin of 14 AFRINIC /24s legitimately held by other operators, and 2013-10-06 to 2013-10-17 mismatch on a LACNIC prefix legitimately held by AS10617; NOT corroborated by any secondary abuse source — treat as unconfirmed

[Likely] — stat.ripe.net routing-history/prefix-overview

CAIDA rank / cone

AS rank 79,459; customer cone = 1 ASN (itself), 0 prefixes, 0 addresses [Confirmed] — CAIDA ASRank API

Analyst note

Encountered as a dormant legacy DoD ASN within the AFCONC-BLOCK1-AS block range (AS379–AS508); no dedicated operator website found. The February 2025 anomalous prefix originations are flagged as unconfirmed routing observations, not an attributed abuse finding, since no secondary security-community source discusses them.