AS104University of Colorado at Boulder
United StatesRegistryARINAs of 22nd October 2026, AS104 (University of Colorado at Boulder), a network registered in the United States with ARIN, originates 21 IPv4 prefixes covering 95.2k addresses and 3 IPv6 prefixes. By IPv4 address space that makes it the 2,475th-largest of the 79,663 networks we see originating IPv4, and the 793rd-largest of 18,476 in the United States. It is seen behind 4 upstream networks, most often AS14041 (University Corporation for Atmospheric…) and AS3356 (Lumen (Level 3)). 8% of its announcements have a valid RPKI ROA; 2 are RPKI-invalid. 92% of its routes reach at least 90% of full-feed peers.
At a glance
IPv4 prefixes
IPv6 prefixes
IPv4 addresses
IPv6 /64s
Upstream graph
The networks AS104 is seen behind, one and two hops out, drawn from real AS paths.
Networks observed one and two hops upstream of AS104 in real AS paths. A thicker line means more vantage points saw that adjacency, so weight tracks how well attested it is — not how much traffic it carries. Adjacency is an observation; whether it is a transit purchase or a settlement-free peering is an inference, and is labelled as one wherever we show it.
Neighbouring networks
8
adjacent networks
- Upstreams
- 450%
- Peers
- 450%
- Downstreams
- 00%
Networks carrying this one's traffic toward the rest of the internet.
| Network | Country | Relationship | Paths | Vantage pts |
|---|---|---|---|---|
| AS14041University Corporation for Atmospheric Research | US | Peer | 845 | 48 |
| AS3356Lumen (Level 3) | US | Peer | 835 | 136 |
| AS149433FM Networks |  BD | Peer | 26 | 13 |
| AS65501 | — | Peer | 4 | 2 |
Prefixes
The largest blocks AS104 originates, widest first.
| Prefix | Addresses | Visibility |
|---|---|---|
| 128.138.0.0/16 | 65.5k | 77/77 |
| 129.19.192.0/18 | 16.4k | 77/77 |
| 129.19.240.0/20 | 4.1k | 77/77 |
| 198.11.16.0/20 | 4.1k | 77/77 |
| 146.5.20.0/22 | 1k | 77/77 |
| 192.12.238.0/24 | 256 | 77/77 |
| 192.12.240.0/24 | 256 | 77/77 |
| 192.12.241.0/24 | 256 | 77/77 |
| 192.12.242.0/24 | 256 | 77/77 |
| 192.12.244.0/24 | 256 | 77/77 |
Routing health
How AS104's own announcements validate against RPKI and how far they propagate. The same measures for the whole routing table are on the routing table in numbers.
RPKI origin validation
- Valid8.3%2
- Invalid8.3%2
- No ROA83.3%20
Propagation
- Globally propagated90% of full-feed peers or more91.7%22
- Partially propagated40% to 90%0.0%0
- Seen by few peersUnder 40%8.3%2
Prefix sizes
IPv4 — 21 prefixes
IPv6 — 3 prefixes
- /324.3B × /6433.3%1
- /424.2M × /6466.7%2
Recent changes
Announcements that started or stopped since 22nd Sept 2026.
No announcement by AS104 started or stopped in this period.
Routing data derived from RouteViews MRT archives, BGPKIT relationship inference and public registry data.