subnet.im

AS399358Anthropic, PBC

United StatesRegistryARIN

As of 27th September 2026, AS399358 (Anthropic, PBC), a network registered in the United States with ARIN, originates 1 IPv4 prefix covering 512 addresses and 2 IPv6 prefixes. By IPv4 address space that makes it the 48,570th-largest of the 79,536 networks we see originating IPv4, and the 10,376th-largest of 18,430 in the United States. It is seen behind 2 upstream networks, most often AS13335 (Cloudflare, Inc.) and AS174 (Cogent Communications, LLC). Every one of its announcements has a valid RPKI ROA, and none are RPKI-invalid. 100% of its routes reach at least 90% of full-feed peers.

At a glance

IPv4 prefixes

1

IPv6 prefixes

2

IPv4 addresses

512

IPv6 /64s

131k

Upstream graph

The networks AS399358 is seen behind, one and two hops out, drawn from real AS paths.

AS399358Toward the internet core
Upstream graph for AS399358: 6 neighbouring networks observed beyond it across 2 levels. The same networks are listed in the tables below.AS399358Anthropic, PBCThis networkAS174Cogent Communicat…AS13335Cloudflare, Inc.AS1299Arelion (fka. Tel…AS151326DCConnect Communi…AS2914NTT America, Inc.AS3356Lumen (Level 3)

Networks observed one and two hops upstream of AS399358 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

5

adjacent networks

Upstreams
240%
Peers
360%
Downstreams
00%

Networks carrying this one's traffic toward the rest of the internet.

Upstreams of AS399358
NetworkCountryRelationshipPathsVantage pts
AS13335Cloudflare, Inc.USPeer147147
AS174Cogent Communications, LLCUSPeer6060

Prefixes

The largest blocks AS399358 originates, widest first.

Largest prefixes originated by AS399358
PrefixAddressesVisibility
160.79.104.0/2351282/82
2607:6bc0::/4865.5k × /6465/65
2607:6bc0:11::/4865.5k × /6460/65

Routing health

How AS399358'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

  • Valid100.0%3
  • Invalid0.0%0
  • No ROA0.0%0

Propagation

  • Globally propagated90% of full-feed peers or more100.0%3
  • Partially propagated40% to 90%0.0%0
  • Seen by few peersUnder 40%0.0%0

Prefix sizes

IPv4 — 1 prefixes

IPv6 — 2 prefixes

  • /4865.5k × /64100.0%2

Recent changes

Announcements that started or stopped since 28th Aug 2026.

No announcement by AS399358 started or stopped in this period.

Routing data derived from RouteViews MRT archives, BGPKIT relationship inference and public registry data.