asn.dev

Autonomous system

AS26101 YAHOO-BF1

Unclassified ARIN

IPv4 addresses 121K 72 prefixes
IPv6 prefixes 4 counted as prefixes, not addresses
Countries 1 mostly US
Exchanges 0 recorded by PCH
Upstreams 1 0 downstream
Flagged prefixes 0 none

Summary

Yahoo

United States of America · AI-generated

business infrastructure corporate

YAHOO-BF1 is the autonomous system for Yahoo Holdings Inc.

What it's used for

  • The address space carries internal corporate infrastructure, evidenced by reverse DNS entries such as et15-1.fab8-2-gdc.bf1.yahoo.com and 254.183.139.98.aprez.ostk.prod.bf1.yahoo.com.
  • The AS announces 121,344 IPv4 addresses across 72 prefixes and 4 IPv6 prefixes, maintaining a single observed neighbour, which indicates a large internal corporate estate rather than a transit or access network.

Notable

  • All registrants for the largest prefixes are listed as Yahoo Holdings Inc., with netnames including A-YAHOO-US9, A-YAHOO-U23, and INKTOMI-BLK-4.
  • The presence of INKTOMI netnames reflects the historical acquisition of Inktomi by Yahoo, which provided the underlying infrastructure for Yahoo's web services.
  • The inventory consists of finely subdivided /20 and /21 blocks, consistent with site-by-site segmentation for a major technology company.

This description is AI-generated, best-effort context — not authoritative, and provided without any guarantee of accuracy. Source, and how to suggest an edit.

Interconnection

Peering at a glance

Full topology · Graph

Internet exchanges

No exchange port on file. Many exchanges publish no participant list, so this is not proof of absence.

Transit providers

1 upstream, 0 downstream and 2 adjacent networks observed; most-used upstreams first.

ASNetworkPaths seen
AS10310Yahoo Holdings Inc.4,804

Exchange presence is recorded rather than inferred: the directory collected by Packet Clearing House (https://www.pch.net/ixp/data) on 2026-10-15, licensed CC BY-NC-SA 3.0. Transit is inferred from observed BGP paths, never declared by either party.

Address space

Summary

Shape and geography

IPv4 72 prefixes · 121K addresses IPv6 4 prefixes

CountryNamePrefixes
USUnited States of America76

Registry

Allocation record

ARIN · via Atlas (registry + RDAP)
Registry
ARIN
Handle
AS26101
Registry name
YAHOO-BF1
Registrant
Yahoo Holdings Inc.
Abuse contact
rir-abuse@yahooinc.com
Registered
2002-07-05
Last changed
2020-07-21
Allocation
assigned

Routing security

RPKI and IRR

Full detail
RPKI
0% valid · 0 valid, 83 with no ROA
ROAs
0 authorising AS26101
ASPA
no ASPA record
IRR
99% registered · 82 of 83 announcements
Route objects
110 naming AS26101

Reputation

Classification and threat

Unclassified Not in the curated lists. Most of the ~80,000 allocated ASNs are not.

Spamhaus DROP

Not on ASN-DROP The network as a whole is not listed.

No DROP prefixes None of its announced space is on the DROP prefix list.

Spamhaus DROP ("Don't Route Or Peer") lists space and networks run by, or hijacked for, spam and cybercrime operations: 442 networks and 1,782 prefixes, as published 2026-10-16. A short, high-confidence list, so a match is worth taking seriously, and absence from it says little on its own.

FBI IC3

No IC3 indicators Nothing from the FBI IC3 feed.

IC3 threat data is alpha. Absence of an indicator is not evidence of good behaviour, only of absence from this one feed.

Elsewhere

Cross-check