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Autonomous System

AS2856 · British Telecommunications Limited

Overview

AS2856 is announced on the Internet: RIPE RIS route collectors currently see 542 IPv4 prefixes and 7 IPv6 prefixes originated by this network. Together, its IPv4 prefixes cover 13,938,688 addresses, with overlapping prefixes counted once. In the paths the collectors record, it has 22 upstream neighbours (transit providers or peers) and 218 downstream neighbours (customers or networks it carries). Its most visible upstreams are British Telecommunications Limited (AS5400), RETN Limited (AS9002), and Zayo Bandwidth (AS6461). AS2856 was assigned by RIPE NCC, and its registration country is United Kingdom.

Source: RIPEstat (RIPE NCC), RIS route collectors. Read on October 16, 2026 at 7:01 PM UTC. This page is refreshed at most every 12 hours.

Go further

Trace a route to this networkOpen in the BGP viewerWHOIS of 86.128.0.1

The trace goes to 86.128.0.1, the first address of 86.128.0.0/10. An address picked inside a prefix may not answer (nothing listens there, or the network filters probes): the trace then shows the path up to the last network that replies.

Announced prefixes

IPv4 prefixes (542 prefixes)

PrefixAddresses
5.35.192.0/212,048
5.80.0.0/15131,072
5.81.0.0/1665,536
5.181.136.0/24256
9.151.0.0/198,192
9.151.208.0/204,096
9.151.248.0/212,048
9.232.192.0/1816,384
9.233.48.0/204,096
9.237.96.0/198,192
9.237.128.0/1816,384
9.237.192.0/198,192
15.145.20.0/221,024
23.26.70.0/24256
23.26.108.0/24256
23.26.117.0/24256
23.26.131.0/24256
23.26.192.0/24256
23.27.32.0/24256
23.27.33.0/24256
23.27.34.0/24256
23.27.35.0/24256
23.27.36.0/24256
23.27.37.0/24256
23.27.38.0/24256
23.27.39.0/24256
23.27.40.0/24256
23.27.102.0/24256
23.27.103.0/24256
23.27.104.0/24256
23.27.105.0/24256
23.27.106.0/24256
23.27.107.0/24256
23.27.108.0/24256
23.230.82.0/23512
23.230.242.0/24256
23.230.252.0/24256
31.48.0.0/13524,288
31.90.0.0/15131,072
31.92.0.0/15131,072
31.94.0.0/1665,536
31.96.0.0/1665,536
31.100.0.0/14262,144
31.104.0.0/1665,536
31.106.0.0/15131,072
31.112.0.0/14262,144
31.116.0.0/14262,144
31.116.0.0/1665,536
31.117.0.0/1665,536
31.118.0.0/1665,536
31.119.0.0/1665,536
31.120.0.0/1665,536
31.121.0.0/1665,536
31.122.0.0/15131,072
31.124.0.0/1665,536
31.126.0.0/15131,072
31.130.240.0/23512
37.44.229.0/24256
37.44.230.0/24256
37.44.231.0/24256
37.97.112.0/221,024
37.143.0.0/221,024
37.230.61.0/24256
40.27.28.0/24256
40.27.72.0/24256
45.39.116.0/24256
45.39.188.0/24256
45.149.7.0/24256
45.149.168.0/23512
45.149.170.0/23512
46.68.0.0/15131,072
46.68.66.0/24256
46.248.96.0/221,024
46.248.102.0/23512
46.248.104.0/23512
46.248.120.0/221,024
50.117.7.0/24256
50.117.51.0/24256
50.118.154.0/23512
51.14.0.0/1665,536
51.64.32.0/24256
51.64.34.0/24256
51.64.35.0/24256
51.146.44.0/221,024
51.146.128.0/221,024
51.146.136.0/221,024
51.146.235.0/24256
51.146.252.0/221,024
51.149.18.0/24256
51.149.19.0/24256
51.194.36.0/23512
51.194.100.0/221,024
51.230.0.0/204,096
51.230.16.0/204,096
51.230.32.0/204,096
51.230.48.0/204,096
51.230.64.0/204,096
51.230.80.0/204,096
51.230.96.0/204,096
51.230.112.0/204,096

Showing the first 100 of 542, in address order. Complete list on RIPEstat

IPv6 prefixes (7 prefixes)

Prefix
2001:4878:c259::/48
2a00:2380::/25
2a01:4c8::/29
2a01:4c8:f400::/48
2a01:4c8:f401::/48
2a02:ee80:4176::/47
2a03:1e82:90ff::/48

Neighbours

Upstreams (transit or peers) (22)

ASNetworkVisibility
AS5400British Telecommunications Limited20,132
AS9002RETN Limited2,984
AS6461Zayo Bandwidth1,008
AS13030Init7 (Switzerland) Ltd.873
AS3303Swisscom (Schweiz) AG643
AS5405Inter.link GmbH581
AS50304Blix Solutions AS411
AS60068Datacamp Limited283
AS4455IX Reach Ltd230
AS6204INTERKVM HOST SRL146
AS8220COLT Technology Services Group Limited139
AS61049Exascale Ltd130
AS9009M247 Europe SRL119
AS30844Liquid Telecommunications Ltd115
AS1267WIND TRE S.P.A.111
AS137409GSL Networks Pty LTD107
AS9505Taiwan Internet Gateway98
AS6206Netrouting B.V.96
AS25180Exponential-E Ltd.60
AS8966EMIRATES TELECOMMUNICATIONS GROUP COMPANY (ETISALAT GROUP) PJSC10
AS48101-1
AS215638Cilix Limited1

Downstreams (customers) (218)

ASNetworkVisibility
AS15248Metaswitch Networks Corp.615
AS39550KPMG LLP523
AS25049Shell Information Technology International B.V.521
AS213786idash IDASH SOLUTIONS LIMITED521
AS33981Total System Services Processing Europe Limited519
AS14766Magnetar Capital LLC507
AS212329Netcraft Ltd362
AS6871Plusnet British Telecommunications Limited359
AS54113Fastly, Inc.358
AS57002William Hill Organization Ltd354
AS197545-353
AS394731-351
AS206051-337
AS201536-334
AS204550-320
AS41570-301
AS9011-291
AS206237-289
AS19428-277
AS28863-275
AS49318-275
AS33127-274
AS3573Accenture LLP273
AS36224-273
AS209761-272
AS15499Computacenter Management GmbH trading as Computacenter AG & Co.oHG271
AS39552-271
AS15141-268
AS29033Eckoh UK Limited267
AS60962-267

The 30 most visible of 218.

166 more neighbours appear on both sides of this network depending on the path, so they are counted in neither list.

Visibility is RIPEstat's count of how often the route collectors observed the link. It compares neighbours with each other; it is not a traffic volume.

How to read this page

An Autonomous System (AS) is a network run under one routing policy: an internet provider, a cloud, a content network, a university. Each one has a number, its ASN, assigned by a regional registry (ARIN, RIPE NCC, APNIC, LACNIC, AFRINIC), and uses BGP, the protocol networks use to tell each other where addresses are, to announce the blocks of addresses it delivers to.

A prefix such as 203.0.113.0/24 is a block of addresses: the number after the slash says how many bits are fixed, so a /24 holds 256 IPv4 addresses and a /16 holds 65,536. Networks often announce a large block and smaller pieces of it at the same time, which is why the address total counts each address once.

Neighbours come from the paths themselves. A network that appears just before this one in a path, on the collector's side, is an upstream: a transit provider or a peer. One that appears just after it is a downstream, usually a customer. Peering at an internet exchange also shows up as an upstream, so the upstream list is not a list of paid transit.

The data comes from RIPEstat, run by the RIPE NCC, which gathers the routing tables of hundreds of networks through its RIS route collectors. This page reads it when it is visited and keeps it for 12 hours at most; the BGP viewer reads it live.

Frequently asked questions

How do I find the ASN of an IP address?
Type the address in the BGP viewer: it shows the prefix that covers it, the AS that originates that prefix and the paths seen towards it. A traceroute also names the network of each hop, so you can see every AS a connection crosses.
Why does one company have several ASNs?
Large operators split their network by region, by activity or by history: a cloud may use one number for its backbone and another for a region, and every acquisition brings its own numbers. Each number has its own page, with its own prefixes and neighbours.
Why do prefix counts differ from one site to another?
Each source sees the routing table from different collectors, at a different time, and counts differently: some include prefixes withdrawn in recent weeks, some merge a block and its pieces. This page counts the prefixes RIPE RIS collectors see originated by the network at the end of the latest two-week window, and counts each IPv4 address once.
Is this the list of IP ranges of a cloud provider?
It is what its networks announce, which is what the Internet routes to them. Many providers also publish an official list of ranges per service and region; that list is the reference for firewall rules, because a range can be announced before it is used, or announced by another of their AS numbers.