AS391

AS391 is a legacy autonomous system number registered under ARIN to Air Force Systems Networking, a U.S. Department of Defense / U.S. Air Force numbering resource administered by DISA (the Defense Information Systems Agency). It does not resolve to a discrete ARIN RDAP autnum object; instead it falls inside a single block registration — handle AS379, ASName AFCONC-BLOCK1-AS, spanning startAutnum 379 through endAutnum 508 — a large sequential DoD allocation dating to the late 1980s. The registrant org (ARIN OrgId 7ESG) lists a Maxwell AFB, Alabama address, and abuse/administrative/technical contact routes to the DISA-Columbus registration group in Whitehall, Ohio. Unlike several dormant siblings in the same block (for example AS389, never announced, and AS390, dormant since 2019), AS391 is actively routed today: RIPEstat reports it as announced with roughly 148 IPv4 prefixes across a large, fragmented portfolio of well-known Air Force /16 blocks (131.15.0.0/16, 137.0.0.0/16, 137.11.0.0/16, 128.202.0.0/16, 128.236.0.0/16, and others), with no IPv6 announcements observed. Its upstream/peer visibility centers on AS27064 (DoD Network Information Center). CAIDA AS Rank could not be retrieved (the lookup timed out), so rank, customer cone, and upstream/peer counts are Unknown. No notable public abuse signal was found as of 2026-07-02 — not in Spamhaus DROP/ASN-DROP, AbuseIPDB, community ASN blocklists, or NANOG archives — consistent with a clean, actively-routed military network whose restricted public visibility (no PeeringDB record, no published peering policy) reflects operational-security posture rather than reputational concern.

Operator

Air Force Systems Networking (U.S. DoD / U.S. Air Force; ARIN OrgId 7ESG; administered by DISA) [Confirmed] — ARIN RDAP autnum/391 (registrant vcard), ipinfo.io/AS391

Country / RIR

US, ARIN [Confirmed] — ARIN RDAP, RIPEstat as-overview (block "1-1876, Assigned by ARIN")

Allocated

1989-08-04 (ARIN registry date from the RDAP autnum TOP-LEVEL events[], handle AS379; NOT an IEEE date — IEEE publishes no ASN registration dates); last changed 2008-06-06 [Confirmed] — ARIN RDAP autnum top-level events (registration / last changed)

Org status

active per ARIN RDAP status array (inherited from the parent AFCONC-BLOCK1-AS block record); no operator-official page confirms current routing use of AS391 specifically [Confirmed for RDAP status] — ARIN RDAP autnum/391

Contacts

DISA-Columbus Registration group, disa.columbus.ns.mbx.arin-registrations@mail.mil, +1-844-347-2457 ext2; 300 North James Road, Whitehall, OH 43213; registrant address 501 East Moore Dr., Bldg 884, Rm 1100, Gunter Annex, Maxwell AFB, AL 36114 [Confirmed] — ARIN RDAP autnum/391

Security/abuse context (NEUTRAL, DATED)

no notable public abuse signal found as of 2026-07-02 — not in Spamhaus DROP/ASN-DROP/SBL, AbuseIPDB, community ASN blocklists (C0nw0nk/ASN-BlackList, bountyyfi/bad-asn-list), or NANOG archives; restricted public visibility reflects military operational-security posture, not reputational concern

Network & routing

Network type

U.S. government/military network (DoD / USAF), administered by DISA; not a commercial ISP, hosting, content, or transit network [Confirmed] — ARIN RDAP, DISA DISN Connection Process Guide

Size

actively routed — ~148 distinct IPv4 prefixes observed in the RIPEstat announced-prefixes window (2026-06-18 → 2026-07-02); large, fragmented DoD-style portfolio (131.15.x, 128.202.0.0/16, 128.236.0.0/16, 137.0.0.0/16, 137.11.0.0/16, 143.141.96.0/22, etc.); no IPv6 announced; address estimate Unknown (no sizing field in source) [Confirmed for v4 prefixes; Unknown for address count] — RIPEstat announced-prefixes

Routing/peering

announced = true [Confirmed]. Observed upstream/peer AS27064 (DoD Network Information Center) [Likely] — bgp.he.net/AS391 (third-party routing observation). No published peering policy; PeeringDB org page (org/20118) does not list AS391 and the direct AS391 network record returns HTTP 404

[Confirmed] — peeringdb.com/asn/391, peeringdb.com/org/20118

RPKI

not assessed — RIPEstat rpki-validation is per-prefix and was self-skipped (no prefix supplied); no per-prefix ROA data retrieved [Unknown] — RIPEstat rpki-validation

AS rank / customer cone / upstreams / peers

Unknown — CAIDA ASRank lookup errored (timeout); no verified page-fetched rank or relationship data. A WebSearch snippet suggesting ~#33,093 global / #2,613 US was NOT corroborated against an opened page and is therefore not recorded [Unknown] — CAIDA ASRank (errored)

Notable usage

no operator-official documentation of specific mission usage; third-party BGP data shows AS391 as a within-block DoD/USAF number carrying established Air Force address space [Confirmed as third-party observation] — bgp.he.net/AS391

Geo footprint

United States — registrant Maxwell AFB, AL; abuse/admin/tech contact DISA-Columbus, Whitehall, OH [Confirmed] — ARIN RDAP autnum/391 vcard data

Related ASNs

sibling within-block DoD ASNs in the AFCONC-BLOCK1-AS range (AS379, AS385, AS386, AS389, AS390, and others through AS508) attributed to Air Force Systems Networking [Likely] — ARIN RDAP block record (AS379, startAutnum 379 → endAutnum 508)

Allocation provenance

AS391 has no discrete RDAP object; it resolves into the shared AFCONC-BLOCK1-AS block record (handle AS379, startAutnum 379 → endAutnum 508). The 1989-08-04 registration is the block's TOP-LEVEL autnum event, recorded per project rule as a first-party RIR fact. Nested entity dates (REGIS10-ARIN reg 2009-06-24; 7ESG org reg 2008-06-05) are org/contact-record dates and were excluded

[Confirmed] — ARIN RDAP autnum/391

Analyst note

Encountered as an actively-routed within-block DoD/USAF ASN sharing a single legacy block registration; distinguished from dormant siblings (AS389/AS390) by live announcements. Registry facts confirmed via ARIN RDAP; routing counts confirmed via RIPEstat; rank/cone Unknown (CAIDA timeout).