AS538

AS538 is a legacy U.S. Department of Defense autonomous system registered under ARIN as DNIC-AS-00538, held by "Headquarters, USAISC" (U.S. Army Information Systems Command). It is a Defense Network Information Center (DNIC) block, not a commercial ISP or content network: the registrant address is Fort Huachuca, Arizona, while day-to-day administrative and abuse contact runs through DISA-Columbus in Whitehall, Ohio. USAISC itself was inactivated as a standalone command in 1996, with its functions folded into what later became U.S. Army NETCOM — so the ASN registration reads as an unmodernized legacy record rather than an actively branded operator. Operationally, AS538 is a small stub network: it announces two IPv4 /24 blocks (192.33.186.0/24 and 192.129.65.0/24, roughly 512 addresses total) with near-full IPv4 RIS visibility, no IPv6 announcements, and an effectively empty customer cone (CAIDA shows zero downstream ASNs, prefixes, or peer/provider degree, while RIPEstat separately counts one observed BGP neighbor). There is no PeeringDB listing for AS538 itself, and no dedicated public operator website exists — sibling USAISC ASNs appear in PeeringDB but AS538 does not. No notable public abuse signal, BGP hijack, route leak, or NANOG community discussion was found as of 2026-07-10, consistent with a low-profile, low-traffic government allocation.

Operator

Headquarters, USAISC (U.S. Army Information Systems Command); registrant "DNIC-AS-00538"; admin/abuse contact DISA-Columbus [Confirmed] — https://rdap.arin.net/registry/autnum/538

Country / RIR

US, ARIN (IANA 16-bit AS block 1-1876, assigned by ARIN) [Confirmed] — https://stat.ripe.net/data/as-overview/data.json?resource=538

Allocated

1989-09-29 — ARIN RDAP autnum TOP-LEVEL registration event (not the nested REGIS10-ARIN entity date of 2009-06-24 or the HEADQU-3 org entity date of 1990-03-26, both decoys); last changed 2011-08-02 [Confirmed] — https://rdap.arin.net/registry/autnum/538

Website

none found; no public operator site for AS538 specifically [Confirmed] — https://en.wikipedia.org/wiki/Army_Network_Enterprise_Technology_Command

Org status

ARIN RDAP status "active" for the registration record itself, but the named registrant command (USAISC) was inactivated in 1996 with functions transferred to successor Army organizations — a legacy, unmodernized record

[Confirmed] — https://rdap.arin.net/registry/autnum/538, https://en.wikipedia.org/wiki/Army_Network_Enterprise_Technology_Command

Contacts

abuse/registration mailbox disa.columbus.ns.mbx.arin-registrations@mail.mil; registrant address Fort Huachuca, AZ 85613; admin/tech address 300 North James Road, Whitehall, OH 43213 [Confirmed] — https://rdap.arin.net/registry/autnum/538

Security/abuse context (NEUTRAL, DATED)

no notable public abuse signal found as of 2026-07-10 across Spamhaus, AbuseIPDB-adjacent search, and NANOG archives; Spamhaus's direct dataset endpoint returned 404 so a definitive "not listed" cannot be fully confirmed, and this is general-search absence-of-evidence, not a direct authoritative-list query

Network & routing

Network type

U.S. federal/military DoD Network Information Center (DNIC) allocation, not a commercial network [Confirmed] — https://rdap.arin.net/registry/autnum/538

Size

2 announced IPv4 /24s (~512 addresses), 0 IPv6 prefixes; customer cone = 1 ASN (itself), 0 prefixes, 0 addresses (stub network) [Confirmed] — https://stat.ripe.net/data/routing-status/data.json?resource=538, https://asrank.caida.org/asns/538

Routing/peering

IPv4 seen by 324/325 RIS peers, IPv6 seen by 0/322; CAIDA AS degree total=0 (customer/peer/provider all 0) while RIPEstat counts 1 observed neighbor — both reported as-is, not reconciled; no PeeringDB network record for AS538 (absent from the 11-ASN "Headquarters, USAISC" org listing that includes sibling ASNs)

[Confirmed] — https://asrank.caida.org/asns/538, https://www.peeringdb.com/org/25069

Peering policy

Unknown / not publicly documented for AS538 itself; cannot be inferred from sibling ASNs' PeeringDB entries [Unknown]

RPKI

Unknown — not tested; RIPEstat rpki-validation requires a specific prefix and was not queried per-prefix in this cycle [Unknown]

Notable usage

announced prefixes 192.33.186.0/24 and 192.129.65.0/24 confirmed via RIPEstat routing data [Confirmed] — https://stat.ripe.net/data/announced-prefixes/data.json?resource=538; third-party ASN databases associate these with Fort Huachuca, AZ (home of Army NETCOM) [Likely] — https://db-ip.com/as538

CAIDA AS rank

79459 [Confirmed] — https://asrank.caida.org/asns/538

Community corroboration

no NANOG mailing-list discussion, documented outages, BGP incidents, or reputation issues found for AS538 [Confirmed] — https://archive.nanog.org/list/archives.html

Analyst note

small dormant-adjacent DoD stub ASN; no operator self-service pages exist to corroborate against, so several fields (website, peering policy, RPKI) are honestly Unknown rather than guessed.