AS104 University of Colorado at Boulder

COLORADO-AS - University of Colorado at Boulder · registered in the United States

IPv4 addresses91,13616 prefixes · 0.003% of announced IPv4

Rank in United States#663largest network in US by IPv4 space, of 18,338 · <0.01% of US

Rank worldwide#1,994of 79,396 networks with IPv4

IPv61 x /32 (65,665 x /48)4 prefixes

CountryUnited States18,679 ASNs registered there

Open AS104 in ASN lookup Look up an IP in this network (128.138.0.1) All networks in United States

IPv4 prefixes

All 16 prefixes, in address order.

128.138.0.0/16
129.19.192.0/18
146.5.20.0/22
192.12.238.0/24
192.12.240.0/23
192.12.242.0/24
192.12.244.0/23
198.11.16.0/20
198.59.7.0/24
198.59.51.0/24
198.59.52.0/24
198.59.54.0/23
198.59.70.0/24
198.59.81.0/24
198.59.82.0/23
204.228.80.0/24

IPv6 prefixes

All 4 prefixes.

2001:468:501::/48
2401:eee0:1c0::/42
2401:eee0:200::/42
2620:18f::/32

Similar-sized networks in United States

ASNNameIPv4 addresses

AS23316#660 BAI-IP-SERVICES - Bel Air Internet, LLC91,904

AS12118#661 WVU - West Virginia University91,648

AS21769#662 AS-COLOAM - Colocation America Corporation91,136

AS33548#664 UNWIRED-NOC - Unwired Broadband, LLC90,880

AS55201#665 SKYQUANTUM-INTERNET-SERVICE - SkyQuantum Internet Service90,368

AS10297#666 ENET-2 - eNET Inc.90,112

IP-to-ASN data: iptoasn.com (public domain). Snapshot downloaded 2026-11-11, refreshed daily. Ranges are what each network announces in BGP, not registry allocations. Data sources