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AS1742Harvard University

United StatesRegistryARIN

As of 23rd October 2026, AS1742 (Harvard University), a network registered in the United States with ARIN, originates 13 IPv4 prefixes covering 205k addresses and 4 IPv6 prefixes. By IPv4 address space that makes it the 1,302nd-largest of the 79,666 networks we see originating IPv4, and the 366th-largest of 18,482 in the United States. It is seen behind 4 upstream networks, most often AS3356 (Lumen (Level 3)) and AS174 (Cogent Communications, LLC), and in front of 2 downstream networks. 88% of its announcements have a valid RPKI ROA, and none are RPKI-invalid. 71% of its routes reach at least 90% of full-feed peers.

At a glance

IPv4 prefixes

13

IPv6 prefixes

4

IPv4 addresses

205k

IPv6 /64s

4.6B

Upstream graph

The networks AS1742 is seen behind, one and two hops out, drawn from real AS paths.

AS1742Toward the internet core
Upstream graph for AS1742: 12 neighbouring networks observed beyond it across 2 levels. The same networks are listed in the tables below.AS1742Harvard UniversityThis networkAS174Cogent Communicat…AS3356Lumen (Level 3)AS11164Internet2 I2PXAS11537Internet2AS1299Arelion (fka. Tel…AS151326DCConnect Communi…AS2914NTT America, Inc.AS3549Lumen (fka. Globa…AS2152CENIC - CalRENAS2497Internet Initiati…AS293ESnetAS2153CENIC

Networks observed one and two hops upstream of AS1742 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

13

adjacent networks

Upstreams
431%
Peers
754%
Downstreams
215%

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

Upstreams of AS1742
NetworkCountryRelationshipPathsVantage pts
AS3356Lumen (Level 3)USPeer1,04360
AS174Cogent Communications, LLCUSPeer951114
AS11164Internet2 I2PXUSPeer25768
AS11537Internet2USPeer552

Prefixes

The largest blocks AS1742 originates, widest first.

Largest prefixes originated by AS1742
PrefixAddressesVisibility
128.103.0.0/1665.5k76/77
131.142.0.0/1665.5k76/77
140.247.0.0/1665.5k76/77
65.112.0.0/204.1k76/77
67.134.204.0/221k76/77
199.94.60.0/221k73/77
140.247.111.0/2425635/77
140.247.152.0/2425635/77
140.247.174.0/2425635/77
140.247.236.0/2425635/77

Routing health

How AS1742'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

  • Valid88.2%15
  • Invalid0.0%0
  • No ROA11.8%2

Propagation

  • Globally propagated90% of full-feed peers or more70.6%12
  • Partially propagated40% to 90%29.4%5
  • Seen by few peersUnder 40%0.0%0

Prefix sizes

IPv4 — 13 prefixes

IPv6 — 4 prefixes

  • /324.3B × /6425.0%1
  • /36268M × /6425.0%1
  • /46262k × /6425.0%1
  • /4865.5k × /6425.0%1

Recent changes

Announcements that started or stopped since 23rd Sept 2026.

No announcement by AS1742 started or stopped in this period.

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