Hosting and cloud
AS3598 is the autonomous system number (ASN) announced by Microsoft Corporation. It announces 90 prefixes, 531,200 IPv4 addresses in total. Every address inside those ranges is routed by this operator, which is what makes the number the shortest answer to who runs a given address.
| Organisation | Microsoft Corporation |
|---|---|
| Autonomous system | AS3598 |
| Network type | Hosting and cloud |
| IPv4 prefixes | 27 |
| IPv6 prefixes | 63 |
| IPv4 addresses | 531,200Summed across every announced prefix. IPv6 is not counted; the numbers are meaningless at that scale. |
| In known VPN ranges | 0 of 27 prefixes |
| In known datacenter ranges | 0 of 27 prefixes |
The last two rows are a second opinion, counted against the X4BNet VPN and datacenter range lists rather than read off the operator name. A network with most of its prefixes in the VPN list is carrying anonymised traffic whatever it calls itself.
The largest ranges Microsoft Corporation announces, biggest first. These are a sample and not the full routing table: 90 prefixes do not fit on a page, and the ones worth showing are the ones most traffic comes from.
| Prefix | Family | Addresses |
|---|---|---|
| 65.53.0.0/16 | IPv4 | 65,536 |
| 131.107.0.0/16 | IPv4 | 65,536 |
| 157.54.0.0/16 | IPv4 | 65,536 |
| 157.57.0.0/16 | IPv4 | 65,536 |
| 157.59.0.0/16 | IPv4 | 65,536 |
| 157.60.0.0/16 | IPv4 | 65,536 |
| 157.58.0.0/17 | IPv4 | 32,768 |
| 167.220.0.0/17 | IPv4 | 32,768 |
| 157.58.128.0/18 | IPv4 | 16,384 |
| 167.220.128.0/18 | IPv4 | 16,384 |
| 157.58.224.0/19 | IPv4 | 8,192 |
| 167.220.192.0/19 | IPv4 | 8,192 |
Live check
The field is prefilled with 65.53.0.1, the first address of the largest range above. Change it for one from your own logs and you get the network, the operator and the verdict for that specific address.
Addresses on Microsoft Corporation are infrastructure: servers, containers and managed services, not people at home. Our engine classifies them datacenter or hosting and never as VPN, because renting a machine is not running a VPN service. It does set anonymized, since a person browsing from a rented server is usually behind a self-hosted VPN, unless the address is known infrastructure such as a public resolver. That distinction matters for what you do next. A signup from here is worth a second look because automation lives on networks like this one, but blocking the range outright also blocks every monitoring service, payment webhook and corporate proxy that runs on it.
The verdict for a single address is never settled by the ASN alone. It is the starting point, and IP Detection adds range membership, behaviour and history on top of it before it answers.
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