AS33538Mimecast North America Inc
United StatesRegistryARINAs of 11th November 2026, AS33538 (Mimecast North America Inc), a network registered in the United States with ARIN, originates 6 IPv4 prefixes covering 2k addresses and 2 IPv6 prefixes. By IPv4 address space that makes it the 25,847th-largest of the 80,747 networks we see originating IPv4, and the 6,393rd-largest of 18,752 in the United States. It is seen behind 3 upstream networks, most often AS6461 (Zayo Bandwidth) and AS3356 (Lumen (Level 3)). 88% of its announcements have a valid RPKI ROA, and none are RPKI-invalid. 50% of its routes reach at least 90% of full-feed peers, and 4 prefixes are also originated by another network.
At a glance
IPv4 prefixes
IPv6 prefixes
IPv4 addresses
IPv6 /64s
Upstream graph
The networks AS33538 is seen behind, one and two hops out, drawn from real AS paths.
Networks observed one and two hops upstream of AS33538 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
6
adjacent networks
- Upstreams
- 350%
- Peers
- 350%
- Downstreams
- 00%
Networks carrying this one's traffic toward the rest of the internet.
| Network | Country | Relationship | Paths | Vantage pts |
|---|---|---|---|---|
| AS6461Zayo Bandwidth | US | Peer | 162 | 100 |
| AS3356Lumen (Level 3) | US | Peer | 68 | 49 |
| AS2914NTT America, Inc. | US | Peer | 51 | 51 |
Prefixes
The largest blocks AS33538 originates, widest first.
| Prefix | Addresses | Visibility |
|---|---|---|
| 170.10.144.0/23 | 512 | 76/76 |
| 170.10.146.0/23 | 512 | 76/76 |
| 41.74.203.0/24 | 256 | 1/76 |
| 170.10.142.0/24 | 256 | 2/76 |
| 216.145.218.0/24 | 256 | 1/76 |
| 216.145.222.0/24 | 256 | 1/76 |
| 2620:134:6006::/48 | 65.5k × /64 | 62/63 |
| 2620:134:6007::/48 | 65.5k × /64 | 62/63 |
Routing health
How AS33538'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
- Valid87.5%7
- Invalid0.0%0
- No ROA12.5%1
Propagation
- Globally propagated90% of full-feed peers or more50.0%4
- Partially propagated40% to 90%0.0%0
- Seen by few peersUnder 40%50.0%4
Prefix sizes
IPv4 — 6 prefixes
IPv6 — 2 prefixes
- /4865.5k × /64100.0%2
Recent changes
Announcements that started or stopped since 12th Oct 2026.
No announcement by AS33538 started or stopped in this period.
Routing data derived from RouteViews MRT archives, BGPKIT relationship inference and public registry data.