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
- Academic allocation +6
- Trust score 71 / 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 |
|---|---|---|---|---|---|---|
| 130.158.0.0/16 | 65.5K |
2.3%
|
University of Tsukuba | JP | Ibaraki | Tsukuba |
| 133.51.0.0/16 | 65.5K |
26.9%
|
University of Tsukuba | JP | Ibaraki | Tsukuba |
| 163.220.252.0/22 | 1.0K |
14.5%
|
University of Tsukuba | JP | — | — |
BGP Announced Prefixes
Live BGP anomalies →Prefixes AS37917 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 |
|---|---|---|
| 130.158.0.0/16 | 34,014 | 2026-07-23 21:27:00 |
| 133.51.0.0/16 | 28,290 | 2026-07-23 21:27:00 |
| 163.220.252.0/22 | 27,448 | 2026-07-23 21:27:00 |
Frequently Asked Questions
What is AS37917?
AS37917 is an Autonomous System Number assigned to University of Tsukuba. 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 AS37917 announce?
AS37917 announces 132.1K IPv4 addresses distributed across 3 routed CIDR prefixes. The network is registered in Japan.
Who operates AS37917?
AS37917 is operated by University of Tsukuba. The organization is based in Japan. You can view all IP ranges and related ASNs on the organization page.
What country is AS37917 registered in?
AS37917 is registered in Japan. This indicates where the network operator is headquartered, though the IP addresses it announces may serve users globally.
