AS306

AS306 is an actively routed ARIN-registered autonomous system held by the United States Department of Defense. It is the lead ASN of the block DNIC-ASBLK-00306-00371 (covering AS306 through AS371), administered through the DoD Network Information Center (DNIC) and operated by the Defense Information Systems Agency (DISA) out of Columbus, Ohio. Unlike many legacy government ASNs, AS306 is not dormant: RIPEstat's announced-prefixes endpoint lists hundreds of live prefixes with timelines running through late June 2026 — roughly 277 IPv4 prefixes and 57 IPv6 prefixes, on the order of 4.6 million IPv4 addresses. The IPv4 space is concentrated in the DoD-held 55.0.0.0/8 supernet and the 132.x.x.x /16 range; the IPv6 space sits in the ARIN-assigned 2608::/12 DoD range, announced largely as /48s with a handful of /40 aggregates. Routing is internal to DoD: observed connectivity is to other autonomous systems inside the AS306–AS371 block and closely affiliated military networks (e.g. AS367, AS1540/USAISC, AS27066), with external commercial reach via contracted transit rather than open peering. There is no public peering policy and no PeeringDB listing; connection to the Defense Information Systems Network (DISN) runs through DoD's own Assessment and Authorization process. Historically the ASN appeared among NANOG's most route-unstable origins in 2006–2007, but no comparable instability or abuse signal appears in modern feeds: CleanTalk, Spamhaus, and abuse.ch/ThreatFox all return clean as of June 2026. AS306 has no RPKI ROAs deployed, a routing-hygiene gap typical of legacy U.S. government networks rather than an abuse indicator.

Operator

United States Department of Defense (DoD), via the DoD Network Information Center (DNIC), operated by DISA; ARIN org handle USDDD [Confirmed] — https://rdap.arin.net/registry/autnum/306, https://whois.arin.net/rest/asn/AS306

Country / RIR

US, ARIN [Confirmed] — RIPEstat abuse-contact-finder (authoritative_rir: arin), https://rdap.arin.net/registry/autnum/306

Allocated

1989-06-30 (ARIN RDAP autnum top-level registration event — RIR first-party date, NOT an IEEE date); last changed 2025-09-12 [Confirmed] — https://rdap.arin.net/registry/autnum/306

Org status

active U.S. federal combat-support agency (DISA); HQ Fort George G. Meade, MD; ARIN mailing address 3990 E. Broad Street, Columbus, OH 43218 [Confirmed] — https://rdap.arin.net/registry/autnum/306, https://en.wikipedia.org/wiki/Defense_Information_Systems_Agency

Contacts

disa.columbus.ns.mbx.hostmaster-dod-nic@mail.mil (NOC/abuse, handle MIL-HSTMST-ARIN); disa.columbus.ns.mbx.arin-registrations@mail.mil (admin/registrations) [Confirmed] — https://rdap.arin.net/registry/autnum/306, RIPEstat abuse-contact-finder

Security / abuse context (NEUTRAL, DATED)

no notable public abuse signal found as of 2026-06-28 — clean on CleanTalk, Spamhaus DROP/ASN-DROP, and ThreatFox/abuse.ch; historical 2006–2007 NANOG BGP instability (route churn, not abuse); bgp.he.net carries a "bogons" flag that current data does not corroborate (0 bogon prefixes observed) [Confirmed for clean feeds; Likely for bogon flag] — https://cleantalk.org/blacklists/as306, https://bgp.he.net/AS306

Network & routing

Network type

U.S. federal government / military network; non-commercial DoD-internal routing domain on the Defense Information Systems Network (DISN); not a commercial ISP or transit provider [Confirmed] — https://rdap.arin.net/registry/autnum/306, https://bgp.tools/as/306

Size

actively routed — ~277 IPv4 prefixes (~4.6M addresses) and ~57 IPv6 prefixes, ~334 prefixes total announced through 2026-06-26 [Confirmed] — RIPEstat announced-prefixes (counts vary slightly by source/date)

Routing / peering

announced and active; upstreams reported as AS367, AS1540 (USAISC), AS27066 (all DoD-affiliated); ~55–58 downstreams; no public peering exchange listing; no published peering policy — connection via DoD's DISN Connection Process Guide [Confirmed for connectivity context; CAIDA upstreams Unknown this run] — https://bgp.he.net/AS306, https://bgp.tools/as/306, https://dl.dod.cyber.mil/wp-content/uploads/connect/CPG/ConnProcGuide.html

RPKI

no ROAs deployed — bgp.he.net shows 0 RPKI-valid and 0 RPKI-invalid origins for both IPv4 and IPv6; per-prefix RPKI validation not performed this run [Confirmed for he.net view; per-prefix Unknown] — https://bgp.he.net/AS306

Notable usage

lead ASN of the DoD DNIC block; underpins NIPRNet and SIPRNet infrastructure under DISA's DISN; the DNIC also operates g.root-servers.net (a logical root nameserver) [Confirmed for block/operator; Likely for g-root attribution per third-party DBs] — https://db-ip.com/as306-dod-network-information-center, https://ipinfo.io/AS306

ARIN handle / block

DNIC-ASBLK-00306-00371 covering AS306–AS371; within the IANA 16-bit range 1–1876 assigned by ARIN [Confirmed] — https://rdap.arin.net/registry/autnum/306

Analyst note

Encountered as an actively routed DoD block lead. ARIN RDAP is authoritative; the top-level autnum events carry registration 1989-06-30 and last-changed 2025-09-12. CAIDA (rank, cone, upstreams) timed out this cycle — those values are Unknown, not zero. RIPEstat as-overview showed announced:false at one snapshot, contradicted by the granular prefix timelines; the prefix data is treated as authoritative on routing state.