AS3598 — MICROSOFT-CORP-AS

AS3598 announces 27 IPv4 prefixes covering 531,200 addresses and 55 IPv6 prefixes.

About this network

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 131.107.0.0/16 and 167.220.0.0/16 ranges 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.

Announced prefixes

• 65.53.0.0/16
• 131.107.0.0/16
• 157.54.0.0/16
• 157.57.0.0/16
• 157.58.0.0/17
• 157.58.128.0/18
• 157.58.192.0/20
• 157.58.208.0/21
• 157.58.217.0/24
• 157.58.218.0/23
• 157.58.220.0/22
• 157.58.224.0/19
• 157.59.0.0/16
• 157.60.0.0/16
• 167.220.0.0/17
• 167.220.128.0/18
• 167.220.192.0/19
• 167.220.224.0/23
• 167.220.228.0/22
• 167.220.232.0/21
• 167.220.240.0/22
• 167.220.248.0/21
• 194.69.96.0/21
• 194.69.106.0/23
• 194.69.108.0/22
• 194.69.112.0/20
• 198.105.232.0/22
• 2001:4898::/32
• 2001:4898:b081::/48
• 2001:4898:b082::/47
• 2001:4898:b084::/46
• 2001:4898:b088::/45
• 2001:4898:b090::/44
• 2001:4898:b0a0::/43
• 2001:4898:b0c0::/42
• 2001:4898:b100::/40
• 2001:4898:b200::/39
• 2001:4898:b400::/38
• 2001:4898:b800::/37
• 2001:4898:c000::/34
• 2404:f801::/32
• 2404:f801:8021::/48
• 2404:f801:8022::/47
• 2404:f801:8024::/46
• 2404:f801:8028::/46
• 2404:f801:802d::/48
• 2404:f801:802e::/47
• 2404:f801:8030::/44
• 2404:f801:8040::/42
• 2404:f801:8080::/41
• 2404:f801:8100::/40
• 2404:f801:8200::/39
• 2404:f801:8400::/38
• 2404:f801:8800::/37
• 2404:f801:9000::/36
• 2404:f801:a000::/35
• 2404:f801:c000::/34
• 2a01:110::/32
• 2a01:110:9009::/48
• 2a01:110:900a::/47
• 2a01:110:900c::/46
• 2a01:110:9010::/44
• 2a01:110:9020::/43
• 2a01:110:9040::/42
• 2a01:110:9080::/41
• 2a01:110:9100::/40
• 2a01:110:9200::/39
• 2a01:110:9400::/38
• 2a01:110:9800::/37
• 2a01:110:a000::/35
• 2a01:110:c000::/34
• 2a01:110:e051::/48
• 2a01:110:e052::/47
• 2a01:110:e054::/46
• 2a01:110:e058::/45
• 2a01:110:e060::/43
• 2a01:110:e080::/41
• 2a01:110:e100::/40
• 2a01:110:e200::/39
• 2a01:110:e400::/38
• 2a01:110:e800::/37
• 2a01:110:f000::/36

Upstream networks

• AS8075 Microsoft Corporation
• AS3356 Level 3 Parent, LLC
• AS2686 AT&T Enterprises, LLC
• AS1680 Cellcom Fixed Line Communication L.P
• AS12849 Hot-Net internet services Ltd.

Adjacent networks

• AS8075 Microsoft Corporation
• AS3356 Level 3 Parent, LLC
• AS2686 AT&T Enterprises, LLC
• AS1680 Cellcom Fixed Line Communication L.P
• AS12849 Hot-Net internet services Ltd.

Routing security

• RPKI: 21 valid, 0 invalid and 2 not-found announcements; 31 ROAs.
• ASPA: none published.
• IRR: 100% of announcements registered; 58 route objects.
• Listed in as-sets: AS-10099, AS-BIX-BG, AS-HOTNET-IL, AS-IGNEMEA, AS-LEARN-8075, AS-MICROSOFT, AS-MICROSOFT, AS-MICROSOFTEU, AS-NV, AS-TELSTRA-INTL-CUSTOMERS-4637, AS-TH-IX-AS45458, AS-THIX, AS58453:AS-ASIAASCUST, AS58453:AS-ASIAASCUST, AS58807:AS-ASIAASCUST, AS58807:AS-ASIAASCUST, AS63830:AS-AKL-IX, AS7606:AS-SA-IX.