AS172

AS172 is a legacy U.S. Department of Defense Autonomous System Number registered through ARIN under the name DNIC-AS-00172 to "Headquarters, USAISC" — the U.S. Army Information Systems Command. The DNIC- prefix marks it as a DoD Network Information Center registration, and the low number reflects an early allocation: ARIN's RDAP record dates the ASN to 1988-04-18, placing it among the earliest-assigned autonomous systems and consistent with the Army's early role in ARPANET-era networking. The registrant command, USAISC, was inactivated in 1996 (re-designated U.S. Army Signal Command), and its lineage later consolidated under the U.S. Army Network Enterprise Technology Command (NETCOM). The ARIN registration has never been updated to a successor command name, so the holder string is historical heritage rather than a live operating organization; day-to-day registry administration now runs through DISA Columbus (Whitehall, OH; technical/abuse contact handle REGIS10-ARIN). The key triage point is routing state: AS172 is dormant. RIPEstat and Hurricane Electric show zero currently announced prefixes (IPv4 and IPv6), zero observed neighbours, and 0 of ~650 RIS peers seeing any route. The only routing on record is a single /24 (104.251.112.0/24) seen roughly November 2018 through June 2019 and flagged a bogon by bgp.he.net. The ASN's ARIN status remains "active" (not revoked; last validated 2026-02-12), and no public abuse, hijack, or blocklist signal was found as of June 2026.

Operator

Headquarters, USAISC (U.S. Army Information Systems Command); ARIN OrgId HEADQU-3, registrant address NETC-ANC CONUS TNOSC, Fort Huachuca, AZ 85613, US [Confirmed] — ARIN RDAP (https://rdap.arin.net/registry/autnum/172)

Country / RIR

US, ARIN [Confirmed] — ARIN RDAP

Allocated

ARIN ASN registration 1988-04-18; ASN last changed 2011-08-24; ARIN last validated 2026-02-12 [Confirmed] — ARIN RDAP (https://rdap.arin.net/registry/autnum/172)

Org status

registrant command USAISC inactivated 1996 (→ U.S. Army Signal Command → NETCOM, 2002); ARIN registration still under the defunct "Headquarters, USAISC" name; ASN allocation active in registry but non-operational in global routing; technical/abuse contact DISA Columbus (REGIS10-ARIN)

[Confirmed] — ARIN RDAP / Wikipedia (NETCOM) / globalsecurity.org

Security/abuse context (NEUTRAL, DATED)

no notable public abuse, BGP-hijack, or blocklist signal found as of 2026-06-17 (Spamhaus DROP/ASN-DROP, AbuseIPDB, community blocklists, NANOG archives, MANRS/Cloudflare/Atlantic Council incident data all clean); confidence in the null is high given the inactive routing state — bgp.he.net / spamhaus.org

Network & routing

Network type

U.S. Federal Government / Military (DoD); legacy, allocated-but-dormant — not currently in the global routing table [Confirmed] — bgp.tools / ipinfo.io / ARIN RDAP

Size

0 IPv4 prefixes and 0 IPv6 prefixes currently announced (0 IPs routed); historically a single /24 (104.251.112.0/24 = 256 IPv4 addrs) [Confirmed] — RIPEstat routing-status / bgp.he.net (2026-06)

Routing/peering

dormant — 0 observed neighbours, no current upstreams or downstreams; one historical peer on record, AS63425 (Group One Consulting, Inc.) during the 2018–2019 active window [routing-status Confirmed; AS63425 peer Likely] — RIPEstat / bgp.he.net

Peering policy

no public peering policy; AS172 is not registered in PeeringDB. The sibling DoD org record (PeeringDB org/25069, "Headquarters USAISC") lists other DNIC ASNs but does NOT include AS172 [Confirmed] — peeringdb.com/org/25069 / bgp.tools

RPKI

not assessable — RIPEstat RPKI-validation skipped (no prefix); bgp.he.net shows 0 valid / 0 invalid / 0 unknown, consistent with zero announcements rather than a confirmed clean ROA posture [Unknown] — bgp.he.net / RIPEstat

AS rank / customer cone

Unknown — not reported by RIPEstat, bgp.he.net, or bgp.tools for a zero-announcement ASN; CAIDA AS-Rank lookup timed out [Unknown]

Historical routing window

first seen 2018-11-03, last seen 2019-06-08 (single prefix 104.251.112.0/24, origin AS172), ~7-month window; prefix flagged bogon by bgp.he.net [Confirmed for window; bogon Likely] — RIPEstat routing-status / bgp.he.net

Notable usage

one of the earliest-assigned ASNs (1988), reflecting the Army's early internet/ARPANET-era infrastructure; the "Headquarters, USAISC" org holds a large DoD ASN portfolio administered by DISA Columbus — networksdb.io / bgp.tools

Related ASNs

sibling DoD DNIC ASNs under the same org/portfolio (e.g., per PeeringDB org/25069: AS13, AS51, AS54, AS153, AS252, AS289, AS305, AS530, AS666, AS1544) [Likely — org grouping per third-party sources, not ARIN-confirmed per-ASN] — peeringdb.com/org/25069

Analyst note

A dormant legacy DoD/Army ASN; WHOIS resolves to the long-defunct "Headquarters, USAISC," with live administration by DISA. No active routing since 2019; clean public reputation. Classified DoD incident data is out of scope for public research.