asn.dev

Autonomous system

AS21369 SEMA-UK-AS

Unclassified RIPE

IPv4 addresses 8.70K 15 prefixes
IPv6 prefixes 0 counted as prefixes, not addresses
Countries 1 mostly GB
Exchanges 0 recorded by PCH
Upstreams 4 0 downstream
Flagged prefixes 0 none

Summary

Atos IT Services UK

United Kingdom · AI-generated

business it-services corporate

SEMA-UK-AS is held by Atos IT Services UK Ltd.

What it's used for

  • The address space carries corporate IT infrastructure, evidenced by reverse DNS entries pointing to uk.atosorigin.com and netnames like UK-ATOSUK-20070407.
  • The AS announces 8704 IPv4 addresses across 15 prefixes with only 4 observed neighbours, indicating a small internal corporate estate rather than a transit or access network.

Notable

  • All registrants for the largest prefixes are consistent with the announcer, listing ATOS Admin and Atos IT Services UK Ltd.
  • Atos is a European multinational IT service and consulting company; this AS represents its UK operational footprint.
  • The inventory consists of finely subdivided /22, /23, and /24 blocks within the 157.203.0.0/16 range, typical of site-by-site corporate segmentation.

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

4 upstream, 0 downstream and 4 adjacent networks observed; most-used upstreams first.

ASNetworkPaths seen
AS198949Radware Ltd1,711
AS8220COLT Technology Services Group Limited528
AS2856British Telecommunications Limited387
AS702Verizon Business72

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 15 prefixes · 8.70K addresses IPv6 0 prefixes

CountryNamePrefixes
GBUnited Kingdom15

Registry

Allocation record

RIPE · via Atlas (registry + RDAP)
Registry
RIPE
Handle
AS21369
Registry name
SEMA-UK-AS
Registrant
Atos IT Services UK Ltd
Abuse contact
uk.abuse@atos.net
Registered
2001-11-15
Last changed
2023-01-03
Allocation
allocated

Routing security

RPKI and IRR

Full detail
RPKI
100% valid · 46 valid, 0 with no ROA
ROAs
48 authorising AS21369
ASPA
no ASPA record
IRR
100% registered · 46 of 46 announcements
Route objects
52 naming AS21369

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