AS503

AS503 is a legacy autonomous system number registered under ARIN as part of the AFCONC-BLOCK1-AS bulk block (AS379–AS508), assigned to Air Force Systems Networking (ARIN Org ID 7ESG) at Maxwell Air Force Base's Gunther Annex, Alabama. The ARIN RDAP autnum record's top-level registration event dates to August 4, 1989, with the record last updated June 6, 2008; day-to-day registry contact duties have since shifted to DISA-Columbus (handle REGIS10-ARIN), reachable at disa.columbus.ns.mbx.arin-registrations@mail.mil. AS503 is currently dormant: every routing source consulted — RIPEstat, CAIDA AS Rank, and live checks against bgp.he.net and bgp.tools — agrees it announces zero IPv4 and zero IPv6 prefixes, has zero observed BGP peers or upstreams, and carries a singleton customer cone (itself only, 0 prefixes, 0 addresses). CAIDA ranks it 79,459th globally, reflecting the total absence of routing activity. No PeeringDB entry exists for AS503 (a direct query to peeringdb.com/asn/503 returned 404), and no dedicated operator website or public peering policy was found; the closest institutional parent today is DISA (disa.mil), which now handles registry-contact administration for this and other bulk-registered military blocks. RPKI posture cannot be assessed since the ASN announces no prefixes to validate. No notable public abuse or threat signal was found for AS503 across Spamhaus DROP/ASN-DROP resources, common bad-ASN blocklists, or NANOG mailing-list archives as of July 2026 — consistent with a registered-but-inactive government network number.

Operator

Air Force Systems Networking (ARIN Org ID 7ESG), member of bulk block AFCONC-BLOCK1-AS (AS379–AS508) [Confirmed] — https://rdap.arin.net/registry/autnum/503

Country / RIR

US, ARIN [Confirmed] — RIPEstat abuse-contact-finder (authoritative_rir: arin)

Allocated

1989-08-04 (ARIN RDAP autnum top-level registration event for the AFCONC-BLOCK1-AS record); last changed 2008-06-06 [Confirmed, corroborated by three independent research angles] — https://rdap.arin.net/registry/autnum/503

Org status

active in ARIN's registry (record present, not revoked) despite zero public routing activity — registered-but-dormant [Confirmed] — https://rdap.arin.net/registry/autnum/503, https://bgp.he.net/AS503

Website

Unknown — no dedicated official operator website found for AS503 specifically; closest institutional parent is disa.mil [Unknown] — https://www.disa.mil/

IANA reference

blank — no applicable RFC found [Unknown]

Security/abuse context (NEUTRAL, DATED)

no notable public abuse signal found as of 2026-07-10 — not in Spamhaus DROP/ASN-DROP resources, common bad-ASN blocklists, or NANOG archives

Network & routing

Network type

U.S. Department of Defense / U.S. Air Force internal government network number; registry contact now administered via DISA-Columbus [Confirmed] — https://rdap.arin.net/registry/autnum/503, https://www.disa.mil/

Size

dormant — 0 IPv4/IPv6 prefixes announced; customer cone = 1 ASN (itself), 0 prefixes, 0 addresses [Confirmed] — RIPEstat routing-status, CAIDA AS Rank, https://bgp.he.net/AS503, https://bgp.tools/as/503

Routing/peering

NOT announced — 0 of 327 v4 RIS peers and 0 of 321 v6 RIS peers see it; CAIDA degree total/customer/peer/provider all 0; no PeeringDB entry (peeringdb.com/asn/503 returned 404) [Confirmed] — https://bgp.tools/as/503, https://www.peeringdb.com/asn/503

RPKI

not assessable — AS503 announces no prefixes, so RIPEstat's rpki-validation check was skipped for lack of a prefix to validate [Unknown/not applicable] — RIPEstat rpki-validation response (skipped)

Notable usage

none public found; low-visibility bulk-registered military ASN with no independent operator-official web presence [Likely] — search coverage exhausted, no fabrication

Registrant address

501 East Moore Dr, Bldg 884 Rm 1100, Gunther Annex, Maxwell AFB, AL 36114, US [Confirmed] — https://rdap.arin.net/registry/autnum/503

Admin/abuse contact

DISA-Columbus (ARIN handle REGIS10-ARIN), disa.columbus.ns.mbx.arin-registrations@mail.mil; phone +1-844-347-2457 ext2 [Confirmed] — https://rdap.arin.net/registry/autnum/503

Analyst note

AS503 is one of a run of sequential ASNs (AS379–AS508) bulk-registered to Air Force Systems Networking in 1989 under one RDAP autnum record; it has never been observed announcing routes in any consulted BGP dataset.