AS21666 OSF Healthcare System

OSF-ASN-01 - OSF Healthcare System · registered in the United States

IPv4 addresses1,0244 prefixes · <0.001% of announced IPv4

Rank in United States#8,279largest network in US by IPv4 space, of 18,338 · <0.01% of US

Rank worldwide#36,663of 79,396 networks with IPv4

IPv6noneno IPv6 routes announced

CountryUnited States18,679 ASNs registered there

Open AS21666 in ASN lookup Look up an IP in this network (38.65.207.1) All networks in United States

IPv4 prefixes

All 4 prefixes, in address order.

38.65.207.0/24
38.131.231.0/24
198.246.176.0/24
204.238.189.0/24

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IP-to-ASN data: iptoasn.com (public domain). Snapshot downloaded 2026-11-11, refreshed daily. Ranges are what each network announces in BGP, not registry allocations. Data sources