AS321

AS321 is a legacy autonomous system number registered under ARIN to the United States Department of Defense (DoD) and managed operationally by the Defense Information Systems Agency (DISA) through the DoD Network Information Center at DISA-Columbus, Ohio. ARIN does not hold a per-ASN record for AS321; instead it returns the block-level autnum DNIC-ASBLK-00306-00371, which covers the contiguous range AS306–AS371 assigned to the DoD. The block's top-level registration event dates to 1989-06-30, with the most recent change recorded 2025-09-12. At query time on 2026-06-28 RIPEstat's as-overview reports the AS as not currently announced, yet the announced-prefixes endpoint shows it was routing very recently — roughly 14 prefixes (13 IPv4, 1 IPv6) carrying active timelines through 2026-06-26 — so the AS cycles in and out of the global table rather than being dormant. Announced space centers on the legacy 55.24.0.0/16 aggregate (labeled "Headquarters, USAISC" by third-party sources) plus DoD Network Information Center allocations under 139.241.0.0/16 and an IPv6 block 2608:14a:3100::/40. Peering is exclusively within the DoD/DISA ecosystem (AS306, AS27064, AS27065, AS27066); there is no PeeringDB record and no commercial transit, consistent with a closed government network. No notable public abuse signal was found as of 2026-06-28 — not in Spamhaus ASN-DROP, CleanTalk, NANOG archives, or community forums — and Scamalytics rates the operator's block at low fraud risk. RPKI coverage is absent at query time, which fits an intermittently announced government AS.

Operator

United States Department of Defense (DoD); ARIN registrant handle USDDD; operationally managed by DISA via the DoD Network Information Center [Confirmed] — https://rdap.arin.net/registry/autnum/321 ; https://ipinfo.io/AS321

Country / RIR

US, ARIN [Confirmed] — https://rdap.arin.net/registry/autnum/321 ; https://stat.ripe.net/data/abuse-contact-finder/data.json?resource=321

Allocated

1989-06-30 (ARIN autnum top-level registration event — RIR first-party fact, NOT an IEEE date; this is the block-level registration for DNIC-ASBLK-00306-00371); last changed 2025-09-12 [Confirmed] — https://rdap.arin.net/registry/autnum/321

Org status

U.S. federal government agency; DISA is a DoD combat support agency (established 1960 as the Defense Communications Agency, renamed DISA 1991), HQ Fort George G. Meade, Maryland [Confirmed] — https://en.wikipedia.org/wiki/Defense_Information_Systems_Agency ; https://www.disa.mil/

Contacts

NOC "Network DoD" — disa.columbus.ns.mbx.hostmaster-dod-nic@mail.mil, +1-844-347-2457 ext 2, DISA-Columbus, 300 North James Road, Whitehall, OH 43213; registrant address 3990 E. Broad Street, Columbus, OH 43218

[Confirmed] — https://rdap.arin.net/registry/autnum/321 ; https://stat.ripe.net/data/abuse-contact-finder/data.json?resource=321

Security/abuse context (NEUTRAL, DATED)

no notable public abuse signal as of 2026-06-28 — not in Spamhaus ASN-DROP, CleanTalk shows 0% spam, no NANOG/Reddit discussions; Scamalytics rates the DoD Network Information Center block at low (0/100) fraud risk. Scattered AbuseIPDB reports on individual IPs in the wider DNIC space (incl. non-routable 11.x.x.x DoD-private) are scanner false-positives, not attributable to AS321 [Confirmed] — https://www.spamhaus.org/drop/asndrop.json ; https://cleantalk.org/blacklists/asn321 ; https://scamalytics.com/ip/isp/dod-network-information-center

Network & routing

Network type

U.S. federal government / military; multi-homed DoD network within the legacy DNIC block; closed government infrastructure (part of the DISA-managed DODIN / DISN, encompassing NIPRNet/SIPRNet) [Confirmed] — https://bgp.he.net/AS321 ; https://en.wikipedia.org/wiki/Defense_Information_Systems_Agency

Size

~13 IPv4 prefixes (~66,000 addresses, dominated by the 55.24.0.0/16 aggregate) and 1 IPv6 prefix (2608:14a:3100::/40) [Confirmed] — https://stat.ripe.net/data/announced-prefixes/data.json?resource=321 ; https://bgp.he.net/AS321

Routing/announcement status

intermittently announced — RIPEstat as-overview reports announced=false at query time 2026-06-28, but announced-prefixes shows active timelines through 2026-06-26; while announced, RIS visibility was near-complete (IPv4 ~99.7%, IPv6 100%) [Confirmed] — https://stat.ripe.net/data/as-overview/data.json?resource=321 ; https://stat.ripe.net/data/announced-prefixes/data.json?resource=321 ; https://stat.ripe.net/data/routing-status/data.json?resource=321

Peering

AS306 (DoD), AS27064 (DISA / DoD Network Information Center), AS27065 (DoD), AS27066 (DoD) — all DoD/DISA-affiliated; no commercial upstreams; no PeeringDB record (HTTP 404); no published peering policy [Confirmed] — https://bgp.he.net/AS321 ; https://bgp.tools/as/321

RPKI

no RPKI coverage at query time — zero RPKI-valid and zero RPKI-invalid originated routes recorded; per-prefix validation not run (no prefix supplied to RIPEstat) [Confirmed] — https://bgp.he.net/AS321

Notable usage

announced space attributed to "Headquarters, USAISC" (U.S. Army Information Systems Command) under 55.24.0.0/16, plus DoD Network Information Center allocations under 139.241.x.0/24 [Confirmed] — https://bgp.he.net/AS321 ; https://bgp.tools/as/321 ; https://ipinfo.io/AS321

Block name

DNIC-ASBLK-00306-00371 (covers AS306–AS371; ARIN returns this block-level autnum for individual ASNs in the range) [Confirmed] — https://rdap.arin.net/registry/autnum/321 ; https://bgp.he.net/AS321

Analyst note

AS321 is one ASN within the DoD block DNIC-ASBLK-00306-00371; entity/contact-level dates in the RDAP record (MIL-HSTMST-ARIN 1993-05-26, REGIS10-ARIN 2009-06-24, USDDD org 2025-03-13) are contact/org dates and are DECOYS — the authoritative allocated_date is the autnum top-level registration 1989-06-30. The bgp.he.net "announces bogons" flag is uncorroborated (55.0.0.0/8 is legitimate DoD space) and treated as a heuristic false positive. Website disa.mil.