AS300

AS300 is a legacy autonomous system number registered under ARIN to the United States Department of Defense (DoD), with the registry name DNIC-AS-00300. The ASN is operated in practice by the DoD Network Information Center (DNIC) under the Defense Information Systems Agency (DISA), the DoD combat-support agency that runs the department's enterprise networks. ARIN's RDAP autnum record carries a top-level registration event of 1989-06-15, making AS300 one of the early, low-numbered government ASNs from the formative period of the public Internet; the autnum was last changed on 2025-09-12. The registrant organization (ARIN org handle USDDD) lists a Columbus, Ohio address, and the administrative and technical contacts route to DISA-Columbus (300 North James Road, Whitehall, OH and 3990 E. Broad Street, Columbus, OH), with abuse and hostmaster mail directed to disa.columbus.ns.mbx.hostmaster-dod-nic@mail.mil. In routing terms AS300 is a tightly held stub network: BGP.he.net and bgp.tools observe a single upstream/peer, AS27064 (DISA), no commercial transit, and roughly 35 IPv4 prefixes (about 96,512 addresses) plus a single IPv6 /48. No Route Origin Authorizations are published (RPKI valid/invalid both zero), and BGP.he.net flags at least one bogon-style prefix — an artifact of historically non-globally-routable DoD address space (e.g. the 214.x.x.x range), not evidence of malicious routing. No notable public abuse signal was found as of June 2026: AS300 is absent from Spamhaus ASN-DROP, the SBL, and open-source ASN blocklists, and the 2021 DoD BGP pilot was conducted through AS8003, not AS300.

Operator

United States Department of Defense (DoD); operated by the DoD Network Information Center (DNIC) under DISA (Defense Information Systems Agency) [Confirmed] — ARIN RDAP autnum/300, bgp.he.net/AS300, bgp.tools/as/300

Country / RIR

US, ARIN [Confirmed] — ARIN RDAP autnum/300; RIPEstat abuse-contact-finder (authoritative_rir: arin)

Allocated

1989-06-15 (ARIN RDAP autnum TOP-LEVEL registration event — first-party RIR fact, NOT a nested entity/org date); last changed 2025-09-12 [Confirmed] — ARIN RDAP autnum/300 top-level events

Org status

U.S. federal government agency (DoD combat-support agency via DISA); not a commercial or non-profit entity [Confirmed] — en.wikipedia.org/wiki/Defense_Information_Systems_Agency

Contacts

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

Website

https://www.disa.mil/ [Confirmed] — en.wikipedia.org/wiki/Defense_Information_Systems_Agency

Security/abuse context (NEUTRAL, DATED)

no notable public abuse signal as of 2026-06 — absent from Spamhaus ASN-DROP (425-entry snapshot, AS300 not present), SBL, and open-source ASN blocklists; no NANOG abuse threads naming AS300; the 2021 DoD honeypot BGP pilot used AS8003, not AS300

Network & routing

Network type

U.S. federal government military network; stub/single-homed AS that does not provide transit [Confirmed] — bgp.tools/as/300, ipinfo.io/AS300, en.wikipedia.org/wiki/Defense_Information_Systems_Agency

Size

~35 IPv4 prefixes (~96,512 addresses) and 1 IPv6 /48 (2608:184::/48) [Confirmed] — bgp.he.net/AS300, bgp.tools/as/300

Routing/peering

announced and active; sole observed upstream/peer is AS27064 (DISA); no commercial transit; average AS path length ~6.160; not seen as transit for any downstream [Confirmed] — bgp.he.net/AS300, bgp.tools/as/300. (RIPEstat as-overview reported announced:false for a point-in-time 2026-06-27 snapshot, but announced-prefixes[] and both bgp.he.net/bgp.tools show active prefixes — treated as a snapshot artifact)

RPKI

no ROAs published — 0 RPKI-valid and 0 RPKI-invalid origins for v4 and v6; route origin not cryptographically validatable [Confirmed] — bgp.he.net/AS300

Notable usage

DISA/DNIC manages DoD enterprise networks (NIPRNet, SIPRNet, JWICS, DISN). DISA also operates G.root-servers.net, one of the 13 authoritative DNS root servers, though that service is not confirmed as originated specifically under AS300 [Likely] — disa.mil, bgp.tools/as/300

Related ASNs

AS27064 (DISA / DoD Network Information Center) — the single upstream/peer [Confirmed] — bgp.he.net/AS300, bgp.tools/as/300

AS rank / customer cone

Unknown — not published by bgp.he.net or bgp.tools for AS300 [Unknown]

Registry name / ARIN handle

DNIC-AS-00300; registrant org handle USDDD [Confirmed] — ARIN RDAP autnum/300

Bogon flag

bgp.he.net flags at least one bogon-style prefix; reflects historically non-globally-routable DoD space (e.g. 214.x.x.x) allocated to DNIC, a routing-filter artifact rather than malicious routing [Confirmed] — bgp.he.net/AS300

Analyst note

Low-numbered legacy DoD ASN; allocated_date 1989-06-15 read from the autnum TOP-LEVEL events array, not the nested USDDD (2007), MIL-HSTMST-ARIN (1993), or REGIS10-ARIN (2009) entity dates. Tightly held stub network, single DISA peer, clean abuse posture.