Autonomous system
AS3598 MICROSOFT-CORP-AS
Unclassified ARIN
Summary
Microsoft Corporation
enterprise legacy
MICROSOFT-CORP-AS is one of Microsoft's long-held AS numbers, registered to One Microsoft Way in Redmond, Washington. It carries Microsoft's corporate-side networks rather than the Azure cloud.
What it's used for
- Microsoft's own corporate and internal networks — the classic
131.107.0.0/16and167.220.0.0/16ranges long associated with Microsoft's corporate and research environments. - Company infrastructure and services that sit outside the public cloud's address space.
Notable
- Corporate, not cloud. Microsoft's public cloud and CDN traffic mostly rides other ASNs; addresses seen under AS3598 are typically Microsoft's own employees, offices, labs, and internal systems.
- Because it is corporate space, an IP here usually means "Microsoft the company" rather than "a customer renting a Microsoft VM" — a useful distinction when attributing traffic.
Interesting
- The low AS number dates from Microsoft's arrival on the routed internet in the early 1990s, well before the company had a cloud business at all.
This description is AI-generated, best-effort context — not authoritative, and provided without any guarantee of accuracy. Source, and how to suggest an edit.
Interconnection
Peering at a glance
Internet exchanges
No exchange port on file. Many exchanges publish no participant list, so this is not proof of absence.
Exchange presence is recorded rather than inferred: the directory collected by Packet Clearing House (https://www.pch.net/ixp/data) on 2026-10-13, licensed CC BY-NC-SA 3.0. Transit is inferred from observed BGP paths, never declared by either party.
Address space
Summary
IPv4 27 prefixes · 531K addresses IPv6 81 prefixes
| Country | Name | Prefixes |
|---|---|---|
| US | United States of America | 108 |
Registry
Allocation record
- Registry
- ARIN
- Handle
AS3598- Registry name
- MICROSOFT-CORP-AS
- Registrant
- Microsoft Corporation
- Abuse contact
- abuse@microsoft.com
- Registered
- 1994-05-18
- Last changed
- 2013-08-21
- Allocation
- assigned
Routing security
RPKI and IRR
- RPKI
- 91% valid · 21 valid, 2 with no ROA
- ROAs
- 31 authorising AS3598
- ASPA
- no ASPA record
- IRR
- 100% registered · 23 of 23 announcements
- Route objects
- 58 naming AS3598
Reputation
Classification and threat
Unclassified Not in the curated lists. Most of the ~80,000 allocated ASNs are not.
Spamhaus DROP
Not on ASN-DROP The network as a whole is not listed.
No DROP prefixes None of its announced space is on the DROP prefix list.
Spamhaus DROP ("Don't Route Or Peer") lists space and networks run by, or hijacked for, spam and cybercrime operations: 436 networks and 1,771 prefixes, as published 2026-10-13. A short, high-confidence list, so a match is worth taking seriously, and absence from it says little on its own.
FBI IC3
No IC3 indicators Nothing from the FBI IC3 feed.
IC3 threat data is alpha. Absence of an indicator is not evidence of good behaviour, only of absence from this one feed.
Elsewhere