AS15404 — COLT Technology Services Group

AS15404 announces 121 IPv4 prefixes covering 141,824 addresses and 10 IPv6 prefixes.

About this network

The netnames read as a customer list: a hospital trust, a patent office, a mobile operator, a manufacturer.

What it's used for

• A business carrier operating across the continent. One hundred and twenty-six IPv4 prefixes and ten IPv6 prefixes announced from the United Kingdom, one hundred and forty-two thousand addresses.

Notable

• Almost none of the netnames name the carrier. They name the organisations whose space it carries: a hospital trust with a netname of forty-two characters, a national patent office on two blocks, a mobile operator on two more, a components manufacturer, and four blocks under one four letter code.
• Several of those customer netnames carry their own country codes and allocation dates, from jurisdictions other than the one the routes are announced from.
• The largest single announcement is a /16, sixty-five thousand addresses in one route.
• Eighteen addresses were queried for reverse DNS and none returned a name.

Interesting

• This is what a business carrier's routing table looks like from outside: a directory of who buys connectivity from it. Each netname is a customer relationship recorded in a public database.
• The hospital trust's block is the one worth pausing on. A /16 of health service address space reaching the internet through a commercial carrier is an ordinary arrangement with an unusual concentration of sensitive traffic behind it.
• Nothing answering in reverse across a network this large is the carrier's choice, and it means the customer names in the registry are the only labels available.

This description is AI-generated, best-effort context — not authoritative, and provided without any guarantee of accuracy.

Announced prefixes

• 5.11.96.0/20
• 45.129.69.0/24
• 46.28.212.0/24
• 51.64.34.0/23
• 62.85.160.0/19
• 62.182.250.0/24
• 77.74.158.0/23
• 85.208.193.0/24
• 91.209.87.0/24
• 91.212.245.0/24
• 91.213.65.0/24
• 91.213.68.0/24
• 91.213.91.0/24
• 91.213.110.0/24
• 91.238.4.0/24
• 91.244.125.0/24
• 109.107.145.0/24
• 129.35.17.0/24
• 129.35.20.0/23
• 129.35.85.0/24
• 139.138.235.0/24
• 141.98.45.0/24
• 148.188.0.0/20
• 148.188.192.0/20
• 148.188.224.0/22
• 148.188.232.0/21
• 155.137.0.0/22
• 155.137.7.0/24
• 156.118.0.0/24
• 156.118.6.0/24
• 156.118.8.0/24
• 157.239.128.0/23
• 158.156.155.0/24
• 158.156.162.0/24
• 158.156.172.0/24
• 158.156.182.0/24
• 158.156.193.0/24
• 161.17.0.0/16
• 163.199.254.0/24
• 170.200.251.0/24
• 170.200.252.0/23
• 170.248.142.0/24
• 170.251.108.0/24
• 170.252.84.0/23
• 170.252.86.0/24
• 176.119.201.0/24
• 178.249.200.0/21
• 185.13.62.0/24
• 185.60.76.0/23
• 185.60.79.0/24
• 185.134.140.0/24
• 185.140.104.0/24
• 185.154.148.0/23
• 185.199.204.0/24
• 185.203.232.0/24
• 185.212.156.0/22
• 185.213.216.0/23
• 185.218.120.0/22
• 185.226.224.0/24
• 185.234.136.0/24
• 188.64.17.0/24
• 188.64.18.0/23
• 192.31.22.0/24
• 192.76.161.0/24
• 192.109.222.0/24
• 192.166.107.0/24
• 192.228.1.0/24
• 192.228.2.0/23
• 192.232.64.0/24
• 192.232.66.0/24
• 193.8.64.0/22
• 193.26.246.0/23
• 193.26.248.0/21
• 193.28.71.0/24
• 193.29.146.0/23
• 193.29.150.0/23
• 193.29.152.0/22
• 193.29.156.0/23
• 193.29.159.0/24
• 193.38.200.0/24
• 193.46.62.0/24
• 193.47.140.0/24
• 193.53.174.0/24
• 193.53.185.0/24
• 193.53.186.0/24
• 193.53.188.0/24
• 193.53.190.0/24
• 193.56.33.0/24
• 193.57.56.0/24
• 193.58.6.0/24
• 193.73.113.0/24
• 193.102.79.0/24
• 193.102.174.0/24
• 193.103.129.0/24
• 193.135.254.0/24
• 193.164.14.0/24
• 193.176.112.0/22
• 193.177.180.0/23
• 193.200.191.0/24
• 194.11.129.0/24

and 31 more.

Upstream networks

• AS8220 COLT Technology Services Group Limited

Adjacent networks

• AS8220 COLT Technology Services Group Limited