AS420

AS420 is a legacy autonomous system number registered under ARIN to Air Force Systems Networking (AFSN), a U.S. Air Force / Department of Defense networking organization administered through DISA-Columbus. It is not a distinct per-ASN record: ARIN RDAP resolves AS420 to a single block-level autnum object, AFCONC-BLOCK1-AS (handle AS379), spanning startAutnum 379 through endAutnum 508 — roughly 130 consecutive ASNs registered as one contiguous range to the same holder (org handle 7ESG, Maxwell AFB, AL). The block's top-level registration event is dated 1989-08-04, last changed 2008-06-06; that block-level registration date is the applicable allocated_date for AS420 as a member of the range. The central triage point is that AS420 is dormant/dark in the public routing system. Every routing source agrees it announces nothing: RIPEstat reports announced=false with zero IPv4 and zero IPv6 prefixes, and 0 of 324 (v4) / 0 of 320 (v6) RIS peers observe it. CAIDA AS Rank confirms seen=false, cliqueMember=false, a bottom-tier rank of 79,459, a singleton customer cone (1 ASN, 0 prefixes, 0 addresses), and an AS degree of zero across customer, peer, and provider. RPKI posture is not assessable because there are no announced prefixes and therefore no ROAs to validate. No notable public abuse signal was found for AS420 as of 2026-07-02 — nothing surfaced in threat-intel aggregators, NANOG archives, or BGP-incident reporting — consistent with an internal/administrative DoD ASN not present on the public Internet.

Operator

Air Force Systems Networking (U.S. Air Force / DoD, administered via DISA-Columbus; RIR org handle 7ESG, Maxwell AFB, AL) [Confirmed] — ARIN RDAP autnum/420

Country / RIR

US, ARIN [Confirmed] — RIPEstat abuse-contact-finder (authoritative_rir: arin), CAIDA country.iso US

Allocated

1989-08-04 (ARIN registry date — RIR registration is a first-party fact, NOT an IEEE date; IEEE publishes no ASN registration dates); last changed 2008-06-06. This is the block-level (AS379–AS508) registration event applicable to AS420 [Confirmed] — ARIN RDAP autnum top-level events

Org status

active per ARIN RDAP status; registrant is the U.S. Air Force (via DISA-Columbus administrative contact); no indication of reassignment, deregistration, or lapse [Confirmed] — ARIN RDAP autnum/420

Contacts

abuse/admin/tech disa.columbus.ns.mbx.arin-registrations@mail.mil; DISA-Columbus, 300 North James Road, Whitehall, OH 43213; registrant org 7ESG at 501 East Moore Dr. Bldg 884 Rm 1100 Gunther Annex, Maxwell AFB, AL 36114 [Confirmed] — ARIN RDAP autnum/420, RIPEstat abuse-contact-finder

Security/abuse context (NEUTRAL, DATED)

no notable public abuse signal found as of 2026-07-02 — no AS420-specific hit in threat-intel aggregators, NANOG archives, or BGP-hijack/route-leak reporting; a direct Spamhaus ASN-DROP feed query was blocked by local tool policy, so Spamhaus is not independently confirmed clean

Network & routing

Network type

government/military enterprise network (U.S. Air Force / DoD internal networking); not a commercial ISP, transit, or content network; AS420 is legacy/inactive [Confirmed] — ARIN RDAP autnum/420, wpafb.af.mil article on AF networking

Size

dormant — 0 IPv4 prefixes / 0 IPv4 addresses and 0 IPv6 prefixes; customer cone = 1 ASN (itself), 0 prefixes, 0 addresses [Confirmed] — RIPEstat routing-status / CAIDA AS Rank (2026-07)

Routing/peering

NOT announced — announced=false; 0 RIS peers seeing it (0/324 v4, 0/320 v6); CAIDA degree total 0 (customer 0, peer 0, provider 0); no upstreams or peers visible [Confirmed]. No public peering policy published for AS420 [Unknown] — RIPEstat as-overview/routing-status, CAIDA AS Rank

RPKI

not assessable — AS420 announces no prefixes, so there are no ROAs to validate; RIPEstat rpki-validation was skipped (requires a prefix parameter, none exist) [Unknown] — RIPEstat rpki-validation (skipped)

Notable usage

AS420 falls within AFCONC-BLOCK1-AS (AS379–AS508), a single ARIN block registered to Air Force Systems Networking, which provides network design, testing, implementation, and enterprise-network sustainment across DoD/Air Force sites (Active Duty, Reserve, Air National Guard, CONUS and OCONUS). Third-party sources show AS420 with no active/visible routed prefixes, domains, or peers, consistent with an internal/administrative DoD ASN

[Likely] — ARIN RDAP autnum/420, ipinfo.io/AS420, wpafb.af.mil

Related ASNs

block members AS379–AS508 (AFCONC-BLOCK1-AS). A PeeringDB org named "Air Force Systems Networking" (org 20118) exists but lists AS65, AS123, AS175, AS221, AS301 — it does NOT list AS420 (directly relevant negative finding) [Confirmed for block range via RDAP; Confirmed for the PeeringDB negative] — ARIN RDAP autnum/420, peeringdb.com/org/20118

Analyst note

Encountered as a dormant legacy ASN served under an ARIN block registration (AS379). Allocated_date read strictly from the autnum TOP-LEVEL events[]; nested entity/org dates (REGIS10-ARIN reg 2009-06-24; org 7ESG reg 2008-06-05) are entity-level decoys and were NOT used. Block-level date is shared across AS379–AS508.