$ query “AS2856” --type=asn → 1 result(s)

AS2856 · BT-UK-AS

British Telecommunications Limited

AS2856 belongs to British Telecommunications Limited and is a major transit provider, established in the United Kingdom in 2002. The system announces a whopping 13.9 million IPv4 addresses (0.37% of routable IPv4 space), including a /10, and supports IPv6. Its primary geographic footprint is in the United Kingdom, with additional presence in Australia and the United States, and smaller footprints in 15 additional countries. This AS has recently updated its prefix announcements.

  • Top 5% — Top 5% of all autonomous systems by reach and degree
  • Space Overlord — Over 10 million IPv4 addresses

Basic Information

Country
🇬🇧 United Kingdom
Category
Internet Service Provider
Network Role
Major Transit
Data Origin
Authoritative — Metadata from authoritative RIR registry (ARIN, RIPE, APNIC, etc.)
Registered
August 30, 2002
Last Changed
June 30, 2026
Last Seen
July 19, 2026 (active)

Prefix Summary

IPv4 Prefixes (raw / aggregated)
490 / 400
IPv6 Prefixes (raw / aggregated)
7 / 5
IPv4 Addresses
13 878 016
Largest IPv4 Prefix
/10 (4 194 304 addresses)
Largest IPv6 Prefix
/25
Geolocated Countries
🇬🇧 United Kingdom (25 710 768 IPs), 🇦🇺 Australia (1 790 032 IPs), 🇺🇸 United States (52 992 IPs) and 15 more
Prefix Changed
July 16, 2026

Reputation

Reputation
Good — 99 flagged IPs out of 13 878 016 total (0.00%)
Open Proxies
1 known open proxies in this network

Connectivity Summary

Upstream Providers
4 upstreams providing transit
Peers
92 networks exchanging traffic without transit
Downstream Customers
151 downstreams buying transit
Unclassified
4 unclassified BGP neighbors
Degree
251 unique BGP neighbors
Reach
159 networks in customer cone

Upstream Providers (4)

Prefix Lists

IPv4 Prefixes (490 total)

  • 86.128.0.0/10 (4 194 304 addresses (/10 prefix))
  • 81.128.0.0/11 (2 097 152 addresses (/11 prefix))
  • 109.144.0.0/12 (1 048 576 addresses (/12 prefix))
  • 217.32.0.0/12 (1 048 576 addresses (/12 prefix))
  • 31.112.0.0/13 (524 288 addresses (/13 prefix))
  • 95.144.0.0/13 (524 288 addresses (/13 prefix))
  • 31.48.0.0/13 (524 288 addresses (/13 prefix))
  • 31.120.0.0/14 (262 144 addresses (/14 prefix))
  • 147.148.0.0/14 (262 144 addresses (/14 prefix))
  • 213.120.0.0/14 (262 144 addresses (/14 prefix))
  • 194.72.0.0/14 (262 144 addresses (/14 prefix))
  • 31.100.0.0/14 (262 144 addresses (/14 prefix))
  • 62.6.0.0/15 (131 072 addresses (/15 prefix))
  • 46.68.0.0/15 (131 072 addresses (/15 prefix))
  • 5.80.0.0/15 (131 072 addresses (/15 prefix))
  • 31.126.0.0/15 (131 072 addresses (/15 prefix))
  • 109.180.0.0/15 (131 072 addresses (/15 prefix))
  • 31.106.0.0/15 (131 072 addresses (/15 prefix))
  • 31.92.0.0/15 (131 072 addresses (/15 prefix))
  • 31.90.0.0/15 (131 072 addresses (/15 prefix))
  • 195.99.0.0/16 (65 536 addresses (/16 prefix))
  • 193.113.0.0/16 (65 536 addresses (/16 prefix))
  • 195.171.0.0/16 (65 536 addresses (/16 prefix))
  • 62.239.0.0/16 (65 536 addresses (/16 prefix))
  • 51.14.0.0/16 (65 536 addresses (/16 prefix))
  • 62.172.0.0/16 (65 536 addresses (/16 prefix))
  • 165.120.0.0/16 (65 536 addresses (/16 prefix))
  • 31.94.0.0/16 (65 536 addresses (/16 prefix))
  • 31.96.0.0/16 (65 536 addresses (/16 prefix))
  • 91.111.0.0/16 (65 536 addresses (/16 prefix))
  • 31.104.0.0/16 (65 536 addresses (/16 prefix))
  • 149.254.0.0/16 (65 536 addresses (/16 prefix))
  • 212.140.0.0/16 (65 536 addresses (/16 prefix))
  • 213.1.0.0/16 (65 536 addresses (/16 prefix))
  • 31.124.0.0/16 (65 536 addresses (/16 prefix))
  • 132.146.0.0/16 (65 536 addresses (/16 prefix))
  • 147.152.0.0/16 (65 536 addresses (/16 prefix))
  • 109.249.0.0/16 (65 536 addresses (/16 prefix))
  • 51.230.0.0/17 (32 768 addresses (/17 prefix))
  • 9.237.128.0/18 (16 384 addresses (/18 prefix))
  • 144.87.128.0/18 (16 384 addresses (/18 prefix))
  • 213.205.192.0/18 (16 384 addresses (/18 prefix))
  • 159.180.96.0/19 (8 192 addresses (/19 prefix))
  • 195.218.32.0/19 (8 192 addresses (/19 prefix))
  • 9.151.0.0/19 (8 192 addresses (/19 prefix))
  • 84.23.0.0/19 (8 192 addresses (/19 prefix))
  • 193.38.192.0/19 (8 192 addresses (/19 prefix))
  • 9.237.96.0/19 (8 192 addresses (/19 prefix))
  • 212.82.0.0/19 (8 192 addresses (/19 prefix))
  • 194.102.0.0/19 (8 192 addresses (/19 prefix))

IPv6 Prefixes (7 total)

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