AS320

AS320 is a legacy autonomous system number registered under ARIN to the United States Department of Defense (DoD). It is not a standalone allocation but one of 66 ASNs (AS306–AS371) inside the block DNIC-ASBLK-00306-00371, administered by the Defense Information Systems Agency (DISA) through the historical DoD Network Information Center (DNIC). ARIN RDAP for autnum/320 redirects to the block-level record, whose top-level registration event is dated 1989-06-30, placing this allocation among the early Internet-era DoD number assignments. The registrant org handle is USDDD (United States Department of Defense), with the NOC/abuse function carried by MIL-HSTMST-ARIN (Network DoD) out of DISA-Columbus in Whitehall, Ohio. Operationally AS320 is a single-homed stub: every routing source consulted shows exactly one observed neighbour and a single BGP peer, AS306 (also DoD), with no transit provided and no PeeringDB presence. The associated address space — 55.25.0.0/16 and the covered sub-prefix 55.25.160.0/22 (IPv4, labeled Headquarters USAISC, the U.S. Army Information Systems Command) plus 2608:16a:3000::/40 (IPv6) — was visible across RIS in the most recent two-week window (2026-06-14 to 2026-06-26) but the as-overview and routing-status snapshots both report announced=false / zero current announced space at the 2026-06-28 query time, indicating the prefixes were withdrawn at that instant. RPKI posture could not be assessed because no prefix was supplied to the validation endpoint. No notable public abuse signal was found as of 2026-06-28 — not in Spamhaus ASN-DROP, CleanTalk, NANOG archives, or AbuseIPDB — consistent with a clean, government-class stub ASN. bgp.he.net carries a "AS320 announces bogons" annotation, but that site's own bogon route report does not list AS320 and no external source corroborates it; 55.0.0.0/8 is a legitimate DoD allocation, so the flag is treated as an uncorroborated heuristic.

Operator

United States Department of Defense (DoD); administered by DISA (Defense Information Systems Agency) via the DoD Network Information Center; ARIN registrant handle USDDD [Confirmed] — ARIN RDAP autnum/320, ipinfo.io/AS320, bgp.he.net/AS320

Country / RIR

US, ARIN [Confirmed] — RIPEstat abuse-contact-finder (authoritative_rir: arin), ARIN RDAP autnum/320

Allocated

1989-06-30 (ARIN registry date — top-level autnum registration event for block DNIC-ASBLK-00306-00371; an RIR first-party fact, NOT an IEEE date); last changed 2025-09-12 [Confirmed] — ARIN RDAP autnum/320 top-level events

Org status

U.S. federal government entity. DISA is a DoD combat support agency (established as Defense Communications Agency 1960-05-12; renamed DISA 1991-06-25; HQ Fort George G. Meade, Maryland) operating the DNIC hostmaster/NOC for the block

[Confirmed] — en.wikipedia.org/wiki/Defense_Information_Systems_Agency, disa.mil, ARIN RDAP

Contacts

NOC/tech/abuse disa.columbus.ns.mbx.hostmaster-dod-nic@mail.mil; phone +1-844-347-2457 ext 2; registrant 3990 E. Broad Street, Columbus, OH 43218; NOC DISA-Columbus, 300 North James Road, Whitehall, OH 43213 [Confirmed] — ARIN RDAP autnum/320, RIPEstat abuse-contact-finder

Security/abuse context (NEUTRAL, DATED)

no notable public abuse signal found as of 2026-06-28 — not in Spamhaus ASN-DROP, CleanTalk (1 email, 0 blacklisted, 0% spam), NANOG archives, or threat feeds; AbuseIPDB block-check returned HTTP 403 (auth wall, single source gap). bgp.he.net "announces bogons" note is uncorroborated by its own bogon report or any external source [Confirmed for clean signal; Likely for bogon-flag dismissal] — spamhaus.org/drop/asndrop.txt, cleantalk.org/blacklists/asn320, bgp.he.net/AS320

Network & routing

Network type

stub AS — single-homed, provides no transit; U.S. federal government / military network within the DoD NIC block DNIC-ASBLK-00306-00371 (AS306–AS371) [Confirmed] — ipinfo.io/AS320, bgp.he.net/AS320, bgp.tools/as/320

Size

IPv4 55.25.0.0/16 (~65,536 addresses; 55.25.160.0/22 is a covered sub-prefix adding no net new IPs) plus IPv6 2608:16a:3000::/40; observed 2026-06-14 to 2026-06-26 then withdrawn — currently 0 announced prefixes at 2026-06-28 query time [Confirmed for prefixes; Likely for address estimate] — RIPEstat announced-prefixes / routing-status

Routing/peering

single-homed — observed_neighbours = 1; sole BGP peer AS306 (also DoD); no public peering policy and no PeeringDB entry for AS320 [Confirmed]. RIS visibility while announced: 324/326 v4 peers (99.4%), 323/323 v6 peers (100%) [Confirmed] — bgp.he.net/AS320, RIPEstat routing-status

RPKI

not assessed — RIPEstat rpki-validation was skipped (no prefix supplied to the endpoint) [Unknown]

Notable usage

IPv4 space 55.25.0.0/16 and 55.25.160.0/22 labeled Headquarters, USAISC (U.S. Army Information Systems Command); part of DISN (Defense Information System Network) infrastructure [Confirmed] — bgp.he.net/AS320, ipinfo.io/AS320, DoD CPG connection-procedures guide

Related ASNs

AS306 (United States Department of Defense — sole observed peer/upstream of AS320); the full block spans AS306–AS371 [Confirmed] — bgp.he.net/AS320, ARIN RDAP autnum/320

Analyst note

Encountered as a single-homed DoD stub ASN inside a legacy DNIC block; allocated date 1989-06-30 read from the top-level autnum events[] (entity/org-level dates 1993/2007/2009/2026 correctly excluded as decoys). Intermittently announced — prefixes were visible in the most recent RIS window but withdrawn at the exact query time. Clean abuse signal.