AS21666
OSF Healthcare System
Reputation · trust score
A transparent 0–100 signal. Every entity starts at a neutral baseline of 65; threat-intel blocklists, exposure, reverse-DNS, routing and allocation each adjust it up or down. Higher is more trustworthy.
- Baseline (neutral) 65
- Trust score 65 / 100
Experimental · trust-vectors model v1.2.0 — a transparent heuristic, not a definitive verdict. How it works →
Top CIDR ranges
| CIDR | IPs | PTR Density | Organization | Country | State | City |
|---|---|---|---|---|---|---|
| 38.65.207.0/24 | 256 |
3.1%
|
OSF Healthcare System | US | — | — |
| 38.131.231.0/24 | 256 |
12.5%
|
OSF Healthcare System | US | Illinois | Peoria |
| 198.246.176.0/24 | 256 |
0.0%
|
OSF Healthcare System | US | — | — |
| 204.238.189.0/24 | 256 |
2.3%
|
OSF Healthcare System | US | Illinois | Peoria |
BGP Announced Prefixes
Live BGP anomalies →Prefixes AS21666 actually originates in BGP, observed across our RIPE RIS collectors. This live routing view can differ from the registry allocation above.
| Prefix | Announcement samples | Last seen |
|---|---|---|
| 38.131.231.0/24 | 12,809 | 2026-08-05 12:15:44 |
| 38.65.207.0/24 | 12,697 | 2026-08-05 12:15:10 |
| 198.246.176.0/24 | 6,483 | 2026-08-05 12:15:44 |
| 204.238.189.0/24 | 4,878 | 2026-08-05 12:15:52 |
Frequently Asked Questions
What is AS21666?
AS21666 is an Autonomous System Number assigned to OSF Healthcare System. An ASN identifies a network that controls a specific set of IP addresses and determines how traffic is routed across the internet via BGP (Border Gateway Protocol).
How many IP addresses does AS21666 announce?
AS21666 announces 1.0K IPv4 addresses distributed across 4 routed CIDR prefixes. The network is registered in United States.
Who operates AS21666?
AS21666 is operated by OSF Healthcare System. The organization is based in United States. You can view all IP ranges and related ASNs on the organization page.
What country is AS21666 registered in?
AS21666 is registered in United States. This indicates where the network operator is headquartered, though the IP addresses it announces may serve users globally.
