AS166
Institute for Defense Analyses
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
- Government allocation +8
- Trust score 73 / 100
Experimental · trust-vectors model v1.1.0 — a transparent heuristic, not a definitive verdict. How it works →
About Institute for Defense Analyses
The Institute for Defense Analyses (IDA) is an American non-profit corporation that administers three federally funded research and development centers (FFRDCs) – the Systems and Analyses Center (SAC), the Science and Technology Policy Institute (STPI), and the Center for Communications and Computing (C&C) – to assist the United States government in addressing national security issues, particularly those requiring scientific and technical expertise. It is headquartered in Alexandria, Virginia.
Top CIDR ranges
| CIDR | IPs | PTR Density | Organization | Country | State | City |
|---|---|---|---|---|---|---|
| 129.246.0.0/16 | 65.5K |
0.1%
|
Institute for Defense Analyses | US | Virginia | Alexandria |
| 164.217.0.0/16 | 65.5K |
0.0%
|
Institute for Defense Analyses | US | Virginia | Alexandria |
| 198.133.241.0/24 | 256 |
0.0%
|
Institute for Defense Analyses | US | — | — |
BGP Announced Prefixes
Live BGP anomalies →Prefixes AS166 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 |
|---|---|---|
| 129.246.235.0/24 | 14,684 | 2026-07-18 10:52:27 |
| 129.246.243.0/24 | 14,682 | 2026-07-18 10:52:27 |
| 129.246.101.0/24 | 14,670 | 2026-07-18 10:52:27 |
| 164.217.228.0/24 | 14,667 | 2026-07-18 10:52:27 |
| 164.217.225.0/24 | 14,664 | 2026-07-18 10:52:27 |
| 129.246.253.0/24 | 14,662 | 2026-07-18 10:52:27 |
| 129.246.230.0/24 | 14,658 | 2026-07-18 10:52:27 |
| 129.246.225.0/24 | 14,651 | 2026-07-18 10:52:27 |
| 164.217.254.0/24 | 14,646 | 2026-07-18 10:52:27 |
| 129.246.229.0/24 | 14,640 | 2026-07-18 10:52:27 |
| 164.217.253.0/24 | 14,636 | 2026-07-18 10:52:27 |
| 129.246.228.0/24 | 14,632 | 2026-07-18 10:52:27 |
| 129.246.254.0/24 | 14,631 | 2026-07-18 10:52:27 |
| 164.217.128.0/17 | 12,324 | 2026-07-18 10:52:27 |
| 129.246.128.0/17 | 12,310 | 2026-07-18 10:52:27 |
| 164.217.0.0/17 | 12,300 | 2026-07-18 10:52:27 |
| 129.246.0.0/17 | 12,294 | 2026-07-18 10:52:27 |
| 198.133.241.0/24 | 9,709 | 2026-07-18 11:01:24 |
Frequently Asked Questions
What is AS166?
AS166 is an Autonomous System Number assigned to Institute for Defense Analyses. 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 AS166 announce?
AS166 announces 131.3K IPv4 addresses distributed across 3 routed CIDR prefixes. The network is registered in United States.
Who operates AS166?
AS166 is operated by Institute for Defense Analyses. The organization is based in United States. You can view all IP ranges and related ASNs on the organization page.
What country is AS166 registered in?
AS166 is registered in United States. This indicates where the network operator is headquartered, though the IP addresses it announces may serve users globally.
