asn.dev

Autonomous system

AS205311 CAMBRIDGE_FIBRE_NETWORKS

Unclassified RIPE

IPv4 addresses 1.28K 2 prefixes
IPv6 prefixes 1 counted as prefixes, not addresses
Countries 1 mostly GB
Exchanges 0 recorded by PCH
Upstreams 1 0 downstream
Flagged prefixes 0 none

Summary

Cambridge Fibre Networks

United Kingdom · AI-generated

residential fibre isp local

CAMBRIDGE_FIBRE_NETWORKS is operated by Cambridge Fibre Networks Ltd.

What it's used for

  • The address space carries full-fibre broadband access, evidenced by the reverse DNS record cfbb001559.b.cam.camfibre.uk and netnames UK-CFN-20170831 and NS-UK-CFN-20260430.
  • The AS announces 1280 IPv4 addresses across 2 prefixes and 1 IPv6 prefix, with only 1 observed neighbour, indicating a local access network rather than a transit provider.
  • Traffic consists of subscriber eyeballs for homes and businesses in Cambridge and surrounding areas, including Newmarket, providing symmetric speeds up to 935 Mbps.

Notable

  • Registrants for both announced prefixes are CFN - Network Operations; Cambridge Fibre Networks Ltd.; Abuse-C Role, which aligns with the AS holder.
  • The address inventory is small and focused on the Cambridge region, consistent with a local independent fibre operator founded in 2016.

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
AS35826Netservers Limited153

Exchange presence is recorded rather than inferred: the directory collected by Packet Clearing House (https://www.pch.net/ixp/data) on 2026-10-30, 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 2 prefixes · 1.28K addresses IPv6 1 prefixes

CountryNamePrefixes
GBUnited Kingdom3

Registry

Allocation record

RIPE · via Atlas (registry + RDAP)
Registry
RIPE
Handle
AS205311
Registry name
Cambridge_Fibre_Networks
Registrant
Cambridge Fibre Networks Ltd.
Abuse contact
abuse@cfn.ltd
Registered
2017-09-25
Last changed
2019-07-03
Allocation
allocated

Routing security

RPKI and IRR

Full detail
RPKI
100% valid · 3 valid, 0 with no ROA
ROAs
3 authorising AS205311
ASPA
1 declared providers
IRR
100% registered · 3 of 3 announcements
Route objects
6 naming AS205311

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: 448 networks and 1,849 prefixes, as published 2026-10-30. 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