AS328

AS328 is a legacy autonomous system number registered under ARIN to the United States Department of Defense (DoD) and administered by the Defense Information Systems Agency (DISA) out of Columbus, Ohio. It does not carry its own per-AS RDAP object; ARIN serves it from the parent block record DNIC-ASBLK-00306-00371 (handle AS306), which spans AS306 through AS371 and is held under the registrant org handle USDDD. The block's top-level autnum registration event is dated 1989-06-30, last changed 2025-09-12 — first-party ARIN registry facts that govern AS328. Operationally AS328 is a stub AS: it has at most a single observed BGP neighbour (AS306, also DoD), no external upstreams, no IXP presence, and no PeeringDB record of its own. RIPEstat's as-overview reported the AS as not currently announcing (announced=false) as of 2026-06-28, though seven IPv4 prefixes — the 55.53.0.0/16 supernet plus six /24s beneath it, totalling 65,536 addresses — were visible through 2026-06-26. The 55.0.0.0/8 space is IANA LEGACY-allocated to the DoD Network Information Center, so bgp.he.net's "announces bogons" notation is best read as a tool artifact for legacy DoD /8 space, not evidence of hijacking. No ROAs exist (RPKI not covered), and no notable public abuse signal was found as of 2026-06-28 across Spamhaus ASN-DROP, ipapi.is, AbuseIPDB, NANOG archives, or GitHub ASN blacklists — consistent with a clean, restricted-visibility U.S. military stub AS.

Operator

United States Department of Defense (DoD), administered by DISA, Columbus, OH; BGP/IPinfo databases label it "DoD Network Information Center" (DNIC) [Confirmed] — ARIN RDAP autnum/328, ipinfo.io/AS328

Country / RIR

US, ARIN (registrant org handle USDDD) [Confirmed] — ARIN RDAP autnum/328, RIPEstat abuse-contact-finder (authoritative_rir: arin)

Allocated

1989-06-30 (ARIN autnum top-level registration event for block DNIC-ASBLK-00306-00371 / handle AS306, which covers AS328 — first-party RIR registry fact, NOT an IEEE date); last changed 2025-09-12 [Confirmed] — ARIN RDAP autnum/328 top-level events

Org status

active U.S. federal government agency; DISA is the registrant administrator; block record actively maintained (last changed 2025-09-12) [Confirmed] — ARIN RDAP autnum/328

Contacts

abuse/hostmaster disa.columbus.ns.mbx.hostmaster-dod-nic@mail.mil; DISA-Columbus, 300 North James Road, Whitehall, OH 43213 [Confirmed] — ARIN RDAP autnum/328, RIPEstat abuse-contact-finder

Website

no dedicated public site for AS328; DISA's site is https://www.disa.mil/; associated domain mail.mil [Confirmed for contact domain; Likely for site mapping] — ipinfo.io/AS328, rdap.arin.net/registry/autnum/328

Security/abuse context (NEUTRAL, DATED)

no notable public abuse signal found as of 2026-06-28 — absent from Spamhaus ASN-DROP, ipapi.is most-abusive list, AbuseIPDB (404), NANOG archives, and GitHub ASN blacklists. bgp.he.net "announces bogons" flag assessed as a tool artifact for IANA-LEGACY 55.0.0.0/8 DoD space, not malicious routing [Confirmed for absence from feeds; Likely for bogon-flag interpretation] — spamhaus.org/drop/asndrop.json, iana.org ipv4-address-space, bgpfilterguide.nlnog.net

Network & routing

Network type

government / military stub AS (single-homed, no transit provided); legacy DoD address space [Confirmed] — ipinfo.io/AS328, bgp.he.net/AS328

Size

7 IPv4 prefixes recently visible (55.53.0.0/16 + six /24s under it ≈ 65,536 addresses); 0 IPv6; as-overview announced=false as of 2026-06-28; prefixes last seen 2026-06-26 [Confirmed] — RIPEstat announced-prefixes / as-overview, bgp.he.net/AS328

Routing/peering

stub AS with at most one observed neighbour, AS306 (also DoD); no external upstreams, no downstream ASes, no IX presence; no public peering policy published [Confirmed] — bgp.he.net/AS328, ipinfo.io/AS328

Routing history

first seen routed ~2008-08-22; last seen 2026-06-26 per RIPEstat routing-status [Likely] — stat.ripe.net/data/routing-status?resource=AS328

RPKI

not covered — 0 valid, 0 invalid; no ROAs found (consistent with legacy government ASes predating RPKI adoption) [Confirmed] — bgp.he.net/AS328

Notable usage

originates the 55.53.0.0/16 block; third-party DBs associate this space with Headquarters, USAISC (U.S. Army Information Systems Command); internal DoD/Army networking; zero IPs respond to ICMP (military OPSEC posture) [Likely] — bgp.he.net/AS328, networksdb.io/ip-addresses-of/headquarters-usaisc

Block / registration

served from parent block DNIC-ASBLK-00306-00371 (AS306–AS371); ARIN does not publish a separate per-AS RDAP object for ASNs inside this DoD block [Confirmed] — ARIN RDAP autnum/328

Analyst note

Encountered as a legacy DoD stub AS within the DNIC block AS306–371. RDAP for /autnum/328 returns the parent block (AS306) record — standard ARIN behaviour for block-assigned ASNs; the block-level 1989-06-30 registration is the authoritative allocated_date. bgp.tools returned HTTP 500 during research.