AS523

AS523 is a legacy Defense Network Information Center (DNIC) autonomous system registered directly with ARIN to "Headquarters, USAISC" — the United States Army Information Systems Command. The RDAP autnum object's top-level registration event dates the allocation to 1989-09-26, with the record last changed 2011-08-24; a separate, later-dated entity underneath the record (the technical/abuse/administrative POC, handle REGIS10-ARIN) carries its own 2009 registration and 2025 last-changed timestamps that belong to that contact object, not to the ASN itself, and were correctly excluded from the allocation date. USAISC as a named Army command was inactivated in 1996, with its functions folded into successor Army signal/network organizations; ARIN's registrant record has never been renamed to reflect that reorganization, which is typical for legacy DoD DNIC holdings. Operationally, AS523 is dormant: three independent routing sources (RIPEstat, Hurricane Electric BGP Toolkit, and CAIDA ASRank) agree it announces zero IPv4 and zero IPv6 prefixes today and has not been visible in the global routing table since 2022-08-09. Historically it originated four IPv4 prefixes with no IPv6, first observed 2000-08-18 and last observed 2022-07-12. No public abuse or hijack signal was found against it.

Operator

Headquarters, USAISC (United States Army Information Systems Command); DNIC/DoD block, technical-abuse-admin POC at DISA Columbus [Confirmed] — https://rdap.arin.net/registry/autnum/523

Country / RIR

US, ARIN [Confirmed] — https://rdap.arin.net/registry/autnum/523

Allocated

1989-09-26 (ARIN RDAP autnum top-level "registration" event); last changed 2011-08-24 [Confirmed] — https://rdap.arin.net/registry/autnum/523, corroborated by third-party WHOIS aggregators (https://ipinfo.io/AS523, https://db-ip.com/as523-headquarters-usaisc)

Org status

ARIN record status "active" (registration held/valid), but operationally dormant since 2022; the originating command, USAISC, was inactivated in 1996 with its functions transferred to successor Army signal/network organizations, and ARIN's registrant record (HEADQU-3, "Headquarters, USAISC") has not been renamed to reflect any successor entity [Likely] — https://rdap.arin.net/registry/autnum/523, https://en.wikipedia.org/wiki/United_States_Army_Information_Systems_Engineering_Command

Contacts

disa.columbus.ns.mbx.arin-registrations@mail.mil (RIPEstat abuse-contact-finder, authoritative RIR: ARIN); registrant address Fort Huachuca, AZ 85613; abuse/technical/admin POC address DISA Columbus, 300 North James Road, Whitehall, OH 43213

[Confirmed] — https://rdap.arin.net/registry/autnum/523, https://stat.ripe.net/AS523

Security/abuse context (NEUTRAL, DATED)

no notable public abuse signal found as of 2026-07-10 — CleanTalk shows 0 detected IPs/0.00% spam rate, not present in the bad-asn-list hosting-abuse blocklist, no Spamhaus DROP/ASN-DROP listing found, no NANOG thread or BGP-hijack event referencing AS523 by number; AbuseIPDB could not be checked directly (fetch blocked, HTTP 403) so that one sub-check stays Unknown rather than asserted clean

Network & routing

Network type

U.S. Department of Defense / U.S. Army network (DNIC allocation), not a commercial ISP or R&E network [Confirmed] — https://rdap.arin.net/registry/autnum/523

Size

currently 0 IPv4/IPv6 prefixes announced and 0 addresses in CAIDA's live cone; IPinfo separately reports a registry-associated allocation of 196,605 IPv4 addresses for this ASN (a distinct, non-live figure — allocated pool vs. currently-routed space) [Confirmed for both figures, distinct meanings] — https://api.asrank.caida.org/v2/restful/asns/523, https://ipinfo.io/AS523

Routing/peering

NOT currently announced — RIPEstat as-overview announced:false, 0/327 v4 and 0/321 v6 RIS peers seeing it, CAIDA asnDegree total/customer/peer/provider all 0; not visible in global BGP since 2022-08-09 per Hurricane Electric [Confirmed] — https://stat.ripe.net/AS523, https://bgp.he.net/AS523. Historically originated 4 IPv4 prefixes (no IPv6), first seen 2000-08-18 (136.205.0.0/16), last seen 2022-07-12 (6.49.0.0/20); one historical BGP peer, AS1541 (also "Headquarters, USAISC")

[Likely] — https://bgp.he.net/AS523

RPKI

not assessable — no announced prefixes, so no ROAs to validate; RIPEstat's rpki-validation check was skipped for lack of a prefix parameter [Confirmed] — https://stat.ripe.net/AS523

Notable usage

DoD/Army DNIC allocation with no public corporate or IR presence; no PeeringDB net record found for AS523 [Confirmed absence] — https://www.peeringdb.com/api/net?asn=523

Related ASNs

AS1541 (sibling "Headquarters, USAISC" DoD ASN, one historically observed peer) [Likely] — https://bgp.he.net/AS523

Analyst note

A DoD/Army DNIC ASN that is registered and administratively active in ARIN but has not carried live BGP traffic since August 2022; no website, no PeeringDB listing, and no abuse history were found, consistent with a quiet, non-public military allocation.