AS351

AS351 is a legacy autonomous system number registered under ARIN to the United States Department of Defense (DoD), operationally administered by the Defense Information Systems Agency (DISA) through the DoD Network Information Center (DNIC) at Columbus, Ohio. The ASN is not individually registered: it falls inside the contiguous block DNIC-ASBLK-00306-00371, which covers AS306 through AS371 and is held as a single ARIN allocation under org handle USDDD. Querying ARIN RDAP for autnum/351 therefore returns the parent block record (handle AS306), whose top-level registration event dates to 1989-06-30 — the authoritative RIR allocated_date — last changed 2025-09-12. AS351 is a stub autonomous system: single-homed, no transit, no downstream customers, and a single observed BGP peer (AS306, also DoD-operated). It originates two IPv4 /16 prefixes (55.37.0.0/16 and 55.84.0.0/16, associated with U.S. Army Information Systems Command space) plus three IPv6 prefixes, for roughly 131,072 IPv4 addresses. RIPEstat's as-overview showed announced: false at one snapshot, but the announced-prefixes endpoint and bgp.he.net both confirm active prefixes with timelines into late June 2026, so the false flag is a stale-snapshot artifact. No notable public abuse signal was found as of 2026-06-28: AS351 is absent from Spamhaus ASN-DROP, unranked by CleanTalk, and carries no AbuseIPDB or NANOG-thread history. Two infrastructure gaps exist — no RPKI ROAs on any announced prefix, and a Hurricane Electric "announces bogons" annotation that BigDataCloud does not corroborate — but neither maps to documented active harm, consistent with a tightly controlled government enclave network.

Operator

United States Department of Defense (DoD); operationally managed by DISA via the DoD Network Information Center (DNIC), DISA-Columbus, OH; ARIN org handle USDDD [Confirmed] — ARIN RDAP autnum/351, ipinfo.io/AS351

Country / RIR

US, ARIN [Confirmed] — ARIN RDAP autnum/351; RIPEstat abuse-contact-finder (authoritative_rir: arin)

Allocated

1989-06-30 (ARIN RDAP autnum top-level registration event for the DNIC-ASBLK-00306-00371 block containing AS351; first-party RIR fact, not an IEEE date); last changed 2025-09-12 [Confirmed] — ARIN RDAP autnum/351 top-level events

Org status

U.S. federal government combat-support agency (DoD); DISA is operational manager of DNIC and all DoD ARIN registrations. Registrant address 3990 E. Broad Street, Columbus, OH 43218; NOC contact disa.columbus.ns.mbx.hostmaster-dod-nic@mail.mil, +1-844-347-2457 ext. 2

[Confirmed] — ARIN RDAP autnum/351, en.wikipedia.org/wiki/Defense_Information_Systems_Agency

Contacts

abuse disa.columbus.ns.mbx.hostmaster-dod-nic@mail.mil; technical NOC DISA-Columbus, 300 North James Road, Whitehall, OH 43213; registrant 3990 E. Broad Street, Columbus, OH 43218 [Confirmed] — ARIN RDAP autnum/351, RIPEstat abuse-contact-finder

Security/abuse context (NEUTRAL, DATED)

no notable public abuse signal as of 2026-06-28 — not in Spamhaus ASN-DROP (425-entry feed checked), not CleanTalk-ranked (top-300), no AbuseIPDB/IPQS hits, no NANOG controversy

Network & routing

Network type

U.S. federal government / military infrastructure; stub AS (single-homed, no transit). DoD IP space administered by DISA-Columbus [Confirmed] — ipinfo.io/AS351, bgp.he.net/AS351

Size

~131,072 IPv4 addresses across two /16 prefixes (55.37.0.0/16, 55.84.0.0/16) plus three IPv6 prefixes (2 IPv4 + 3 IPv6 announced) [Confirmed] — bgp.he.net/AS351, RIPEstat announced-prefixes (resource=AS351)

Routing/peering

stub AS; sole observed BGP peer is AS306 (also DoD); no external transit upstreams, no IX presence, no public peering policy. RIPEstat as-overview showed announced:false at one snapshot — a stale-snapshot artifact; announced-prefixes and bgp.he.net confirm live prefixes through late June 2026 [Confirmed for AS306 peer; Likely for "no external upstream"] — bgp.he.net/AS351, RIPEstat announced-prefixes

RPKI

no ROAs — 0 valid, 0 invalid; all announced prefixes are RPKI-unprotected. bgp.he.net additionally flags AS351 as announcing bogons; BigDataCloud shows 0 bogon prefixes for the same ASN (discrepancy, no documented harm) [Confirmed for no-ROA; Likely for bogon annotation] — bgp.he.net/AS351, bigdatacloud.com/asn-lookup/AS351

Related ASNs

AS306 (sole peer, same DoD/DNIC block and intra-block upstream); broader USDDD portfolio of ~20+ DoD ASNs within the 306–371 block [Confirmed for AS306; Likely for broader portfolio per third-party DB] — bgp.he.net/AS351, whois.ipip.net/AS351

Block / assignment

DNIC-ASBLK-00306-00371 (AS306–AS371), held as a single contiguous ARIN allocation; AS351 is not individually registered — RDAP returns the parent block record (handle AS306) [Confirmed] — ARIN RDAP autnum/351

Analyst note

Encountered as a quiet, single-peer DoD stub ASN inside the legacy DNIC-ASBLK-00306-00371 block; clean reputation, but no RPKI ROAs and an unresolved HE bogon flag. CAIDA AS Rank / customer cone unavailable (CAIDA API returned HTTP 502).