AS371

AS371 is a legacy autonomous system number registered under ARIN to the United States Department of Defense (DoD) and operated by the DoD Network Information Center (DNIC). It is not registered as a standalone ASN: ARIN records it inside the block object DNIC-ASBLK-00306-00371, which spans AS306 through AS371 and returns a single RDAP autnum record (handle AS306) covering the whole numeric range — standard ARIN practice for legacy DoD military blocks. The registrant org is the "United States Department of Defense (DoD)" (org handle USDDD, 3990 E. Broad Street, Columbus, OH), with operational NOC/technical/abuse and registration contacts both listing DISA-Columbus (the Defense Information Systems Agency facility at 300 North James Road, Whitehall, OH). Operationally, AS371 is a government/military network classified as a stub AS: IPinfo tags it ASN Type "Government," and BGP-observation sites show its only visible adjacency is to AS306 (also DoD), i.e. it behaves as an internal segment of DoD's own DNIC block rather than a network with third-party peers. It originates IPv4 space within DoD's legacy 55.0.0.0/8 block — RIPEstat shows announcements under 55.95.0.0/16 (with several transient /21 and /22 sub-prefixes), and no IPv6. The ASN is announced and active. No notable public abuse signal was found as of 2026-07-02, and — importantly — AS371 is a different ASN from AS8003/AS749, the DoD Network Information Center ASNs specifically named in the January 2021 Defense Digital Service BGP-advertisement pilot; that event is not attributable to AS371.

Operator

DoD Network Information Center (DNIC); registrant org United States Department of Defense (DoD), org handle USDDD; operated at DISA-Columbus [Confirmed] — ARIN RDAP (rdap.arin.net/registry/autnum/371), ipinfo.io/AS371

Country / RIR

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

Allocated

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

Org status

active; ARIN RDAP autnum status "active" [Confirmed] — ARIN RDAP

Contacts

abuse/hostmaster disa.columbus.ns.mbx.hostmaster-dod-nic@mail.mil; registrations disa.columbus.ns.mbx.arin-registrations@mail.mil; DISA-Columbus, 300 North James Road, Whitehall, OH 43213; registrant org 3990 E. Broad Street, Columbus, OH 43218 [Confirmed] — ARIN RDAP, RIPEstat abuse-contact-finder

Security/abuse context (NEUTRAL, DATED)

no notable public abuse signal found as of 2026-07-02 — not in Spamhaus, AbuseIPDB, NANOG archives, or general security press; no AS371-specific listings, hijacks, or campaign attributions. Do NOT conflate with AS8003/AS749 (the DoD ASNs named in the Jan-2021 Defense Digital Service BGP pilot) — that event is not AS371

Network & routing

Network type

government / military network; classified Government / stub AS (single-homed, no transit); internal segment of DoD's DNIC block [Confirmed] — ipinfo.io/AS371, bgp.tools/as/371

Size

RIPEstat announced-prefixes shows IPv4 within 55.95.0.0/16 (plus transient 55.95.156.0/22, 55.95.160.0/22, 55.95.208.0/21, 55.95.216.0/21 in the fetch window); the /16 covers the sub-blocks, so distinct routed space is effectively one /16 (~65,536 addresses); 0 IPv6 [Confirmed IPv4 /16; Likely for 0 IPv6 — payload truncated before an explicit v6 check] — RIPEstat announced-prefixes

Routing/peering

announced=true; only visible adjacency is AS306 (also DoD) per BGP-observation sites; no public operator-published peering policy for AS371 or DNIC (bgp.tools shows only a generic "Global Aggregation Policy" label, not operator text) [Confirmed for AS306 adjacency; Unknown for a published peering policy] — bgp.tools/as/371, ipinfo.io/AS371

RPKI

not assessed — RIPEstat rpki-validation was skipped (requires a specific --prefix argument not supplied); genuinely unqueried, not absent [Unknown] — RIPEstat rpki-validation (skipped)

AS rank / customer cone / upstreams / peer sample

Unknown — RIPEstat routing-status payload was truncated before peer/rank data and CAIDA ASRank was not queried; web searches for bgp.he.net/AS371 and bgp.tools/as/371 returned only adjacent DoD-block ASNs, not AS371 specifically [Unknown — not fabricated] — RIPEstat routing-status (truncated)

Notable usage

originates IPv4 within DoD's legacy 55.0.0.0/8 space (55.95.0.0/16); no IPv6, no hosted domains reported; ranked far down global ASN traffic rankings (~#40,884 per IPinfo), consistent with a low-visibility internal DoD segment [Confirmed] — ipinfo.io/AS371, bgp.tools/as/371

Related ASNs

AS306 (block partner / only visible adjacency, also DoD); AS371 sits within the AS306–AS371 DNIC block; the DoD Network Information Center operates many other ASNs (e.g. AS138, AS313, AS721, AS749, AS8003) [Confirmed for AS306; Likely for the broader DoD ASN list per third-party sources] — ARIN RDAP, ipinfo.io

Analyst note

Encountered as a legacy DoD ASN inside a block-registered DNIC object; the RDAP query for /autnum/371 returns the block record (handle AS306, name DNIC-ASBLK-00306-00371), so the 1989-06-30 top-level registration date is the authoritative allocated_date for AS371. Entity-level dates (USDDD 2007-01-12, MIL-HSTMST-ARIN 1993-05-26, REGIS10-ARIN 2009-06-24) are contact/org record dates and were correctly excluded from allocated_date.