AS551

AS551 is a long-registered autonomous system number allocated under ARIN to Parsons Corporation, a US engineering, defense, intelligence, and critical-infrastructure solutions contractor founded in 1944 and today headquartered in Centreville, Virginia (NYSE: PSN). The ARIN registration itself dates to 1989-11-13, with the record last updated 2015-07-02; the registrant address on file (100 W. Walnut Street, Pasadena, CA 91124) reflects the ASN's older registration era rather than Parsons' current headquarters. Parsons is not a network operator or ISP — no PeeringDB record exists for AS551, and no peering policy, network page, or ASN documentation appears anywhere on parsons.com. Consistent with that, every routing source consulted (RIPEstat routing-status, CAIDA AS Rank, and the supplied canonical RDAP/RIPEstat/CAIDA snapshot) agrees AS551 is currently dormant: zero announced IPv4 and IPv6 prefixes, zero of 327 RIS peers seeing it on v4 and zero of 322 on v6, zero CAIDA degree (customer/peer/provider all 0), and a customer cone limited to the ASN itself. CAIDA AS Rank places it at 79,459, near the bottom of the global ranking. No notable public abuse signal was found across Spamhaus ASN-DROP context pages, AbuseIPDB, blocklist.de, CleanTalk, or NANOG mailing-list archives, consistent with a quiet, unrouted legacy ASN rather than an actively abused one.

Operator

Parsons Corporation (US engineering/defense/critical-infrastructure contractor, founded 1944; NYSE: PSN) [Confirmed] — https://www.parsons.com/, https://rdap.arin.net/registry/autnum/551

Country / RIR

US, ARIN [Confirmed] — https://rdap.arin.net/registry/autnum/551, https://stat.ripe.net/AS551

Allocated

1989-11-13 (ARIN RDAP autnum top-level registration event, first-party RIR fact, corroborated by whois.ipip.net); last changed 2015-07-02 [Confirmed] — https://rdap.arin.net/registry/autnum/551, https://whois.ipip.net/AS551

Org status

Parsons Corporation is an active, publicly traded company (NYSE: PSN); the AS551 registration is marked "active" at ARIN but the ASN itself is operationally dormant (not currently routed) [Confirmed] — https://rdap.arin.net/registry/autnum/551, https://bgp.tools/as/551

Contacts

Hostmaster@parsons.com; +1-800-252-8108; registrant org handle PCIP; admin/tech/abuse entity handle HO35-ORG-ARIN; registered address 100 W. Walnut Street, Pasadena, CA 91124 (legacy registration address, not current HQ) [Confirmed] — https://rdap.arin.net/registry/autnum/551

Security/abuse context (NEUTRAL, DATED)

no notable public abuse signal found as of 2026-07-11 across Spamhaus ASN-DROP, AbuseIPDB, blocklist.de, CleanTalk ASN stats, or NANOG archives

Network & routing

Network type

not classifiable as a public network operator type (Content/Transit/Enterprise-peering, etc.); no PeeringDB record (peeringdb.com/asn/551 returns 404) and no operator-published network documentation found — appears to be an internal/enterprise ASN not currently announcing routes

[Likely] — https://www.peeringdb.com/asn/551, https://bgp.tools/as/551

Size / routing status

dormant — 0 IPv4 and 0 IPv6 prefixes announced; customer cone = 1 ASN (itself), 0 prefixes, 0 addresses [Confirmed] — https://stat.ripe.net/AS551, https://asrank.caida.org/asns/551

Routing/peering

NOT currently announced — 0/327 RIS peers seeing it on v4, 0/322 on v6; CAIDA degree total 0 (customer 0, peer 0, provider 0); no peering policy publicly documented [Confirmed] — https://stat.ripe.net/AS551, https://asrank.caida.org/asns/551

RPKI

not assessable — AS551 announces no prefixes, so there is nothing to validate against [Unknown] — no source

Notable usage

no notable public usage or traffic figures found; AS551 has no observable current traffic footprint given zero announced prefixes [Likely] — https://bgp.tools/as/551

Analyst note

Long-dormant, ARIN-registered ASN held by a non-network-operator engineering/defense contractor; no PeeringDB, peering policy, or public routing presence — consistent with a reserved/unrouted enterprise ASN.