Autonomous System
AS1221 · Telstra Limited
Overview
AS1221 is announced on the Internet: RIPE RIS route collectors currently see 281 IPv4 prefixes and 2 IPv6 prefixes originated by this network. Together, its IPv4 prefixes cover 13,400,320 addresses, with overlapping prefixes counted once. In the paths the collectors record, it has 11 upstream neighbours (transit providers or peers) and 301 downstream neighbours (customers or networks it carries). Its most visible upstreams are Telstra Global (AS4637), F5 Networks SARL (AS35280), and SingTel Optus Pty Ltd (AS7474). AS1221 was assigned by ARIN, and its registration country is Australia.
Source: RIPEstat (RIPE NCC), RIS route collectors. Read on October 16, 2026 at 11:01 PM UTC. This page is refreshed at most every 12 hours.
Go further
The trace goes to 1.128.0.1, the first address of 1.128.0.0/11. 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 (281 prefixes)
| Prefix | Addresses |
|---|---|
| 1.120.0.0/13 | 524,288 |
| 1.128.0.0/11 | 2,097,152 |
| 58.160.0.0/12 | 1,048,576 |
| 60.224.0.0/13 | 524,288 |
| 61.8.0.0/19 | 8,192 |
| 61.9.128.0/17 | 32,768 |
| 66.111.164.0/24 | 256 |
| 66.111.166.0/24 | 256 |
| 66.111.168.0/24 | 256 |
| 66.111.171.0/24 | 256 |
| 66.111.173.0/24 | 256 |
| 101.103.0.0/16 | 65,536 |
| 101.160.0.0/11 | 2,097,152 |
| 103.58.34.0/24 | 256 |
| 103.58.35.0/24 | 256 |
| 103.58.212.0/24 | 256 |
| 103.78.241.0/24 | 256 |
| 103.136.214.0/24 | 256 |
| 103.136.215.0/24 | 256 |
| 103.149.43.0/24 | 256 |
| 103.195.64.0/24 | 256 |
| 103.226.244.0/23 | 512 |
| 103.247.118.0/23 | 512 |
| 103.247.118.0/24 | 256 |
| 103.247.119.0/24 | 256 |
| 110.140.0.0/15 | 131,072 |
| 110.142.0.0/16 | 65,536 |
| 110.143.0.0/16 | 65,536 |
| 110.144.0.0/13 | 524,288 |
| 120.144.0.0/13 | 524,288 |
| 120.152.0.0/14 | 262,144 |
| 120.156.0.0/15 | 131,072 |
| 120.158.0.0/16 | 65,536 |
| 121.208.0.0/12 | 1,048,576 |
| 122.200.24.0/23 | 512 |
| 123.209.0.0/16 | 65,536 |
| 123.210.0.0/15 | 131,072 |
| 124.176.0.0/12 | 1,048,576 |
| 125.255.0.0/16 | 65,536 |
| 136.238.200.0/24 | 256 |
| 137.147.0.0/16 | 65,536 |
| 138.130.0.0/16 | 65,536 |
| 138.217.0.0/16 | 65,536 |
| 139.130.0.0/16 | 65,536 |
| 139.134.0.0/16 | 65,536 |
| 139.168.0.0/16 | 65,536 |
| 143.223.18.0/24 | 256 |
| 143.223.87.0/24 | 256 |
| 143.238.0.0/16 | 65,536 |
| 144.130.0.0/17 | 32,768 |
| 144.130.144.0/20 | 4,096 |
| 144.130.160.0/19 | 8,192 |
| 144.130.192.0/18 | 16,384 |
| 144.131.0.0/16 | 65,536 |
| 144.132.0.0/14 | 262,144 |
| 144.136.0.0/15 | 131,072 |
| 144.139.0.0/16 | 65,536 |
| 144.140.0.0/16 | 65,536 |
| 146.144.9.0/24 | 256 |
| 147.69.0.0/16 | 65,536 |
| 148.80.1.0/24 | 256 |
| 149.135.0.0/16 | 65,536 |
| 149.176.112.0/24 | 256 |
| 149.176.116.0/24 | 256 |
| 149.176.172.0/24 | 256 |
| 149.176.221.0/24 | 256 |
| 149.176.223.0/24 | 256 |
| 149.176.225.0/24 | 256 |
| 149.176.226.0/24 | 256 |
| 149.176.227.0/24 | 256 |
| 149.176.244.0/24 | 256 |
| 149.176.246.0/24 | 256 |
| 149.176.248.0/24 | 256 |
| 149.176.250.0/24 | 256 |
| 149.176.251.0/24 | 256 |
| 149.176.252.0/24 | 256 |
| 149.176.253.0/24 | 256 |
| 149.176.254.0/24 | 256 |
| 149.176.255.0/24 | 256 |
| 156.22.1.0/24 | 256 |
| 156.22.2.0/24 | 256 |
| 158.45.0.0/22 | 1,024 |
| 158.45.13.0/24 | 256 |
| 158.45.14.0/24 | 256 |
| 158.45.60.0/22 | 1,024 |
| 158.45.100.0/24 | 256 |
| 158.45.104.0/24 | 256 |
| 158.45.112.0/24 | 256 |
| 158.45.116.0/24 | 256 |
| 158.45.120.0/24 | 256 |
| 158.146.145.0/24 | 256 |
| 158.146.152.0/24 | 256 |
| 159.222.184.0/24 | 256 |
| 160.187.61.0/24 | 256 |
| 164.108.9.0/24 | 256 |
| 164.108.10.0/24 | 256 |
| 164.108.12.0/24 | 256 |
| 164.108.13.0/24 | 256 |
| 164.108.17.0/24 | 256 |
| 164.108.24.0/22 | 1,024 |
Showing the first 100 of 281, in address order. Complete list on RIPEstat
IPv6 prefixes (2 prefixes)
| Prefix |
|---|
| 2001:8000::/20 |
| 2401:a480::/48 |
Neighbours
Upstreams (transit or peers) (11)
| AS | Network | Visibility |
|---|---|---|
| AS4637 | Telstra Global | 108,675 |
| AS35280 | F5 Networks SARL | 367 |
| AS7474 | SingTel Optus Pty Ltd | 23 |
| AS7545 | TPG Telecom Limited | 4 |
| AS4826 | Vocus Connect International Backbone | 3 |
| AS38561 | NTT Australia Solutions Pty Ltd | 3 |
| AS17559 | Spectrums Core Network | 2 |
| AS38195 | Superloop | 2 |
| AS10026 | Telstra Global Internet Services Network Blocks | 1 |
| AS63956 | 5G NETWORK OPERATIONS PTY LTD | 1 |
| AS149515 | - | 1 |
Downstreams (customers) (301)
| AS | Network | Visibility |
|---|---|---|
| AS4637 | Telstra Global | 110,703 |
| AS9507 | NextHop Pty Ltd | 9,437 |
| AS4764 | Aussie Broadband | 8,016 |
| AS20473 | The Constant Company, LLC | 7,611 |
| AS49915 | Megaport (UK) Limited | 4,206 |
| AS20940 | Akamai International B.V. | 3,464 |
| AS15830 | Equinix Equinix (EMEA) Acquisition Enterprises B.V. | 2,937 |
| AS60068 | Datacamp Limited | 2,312 |
| AS63956 | 5G NETWORK OPERATIONS PTY LTD | 2,230 |
| AS45437 | Real World - The Core | 2,216 |
| AS21859 | Zenlayer Inc | 1,386 |
| AS58511 | Anycast Global Backbone | 1,276 |
| AS132847 | - | 1,161 |
| AS23918 | - | 957 |
| AS3360 | DXC US Latin America Corporation | 821 |
| AS133934 | - | 802 |
| AS135879 | - | 780 |
| AS139049 | - | 748 |
| AS18055 | - | 728 |
| AS4608 | - | 705 |
| AS3573 | Accenture LLP | 676 |
| AS45926 | - | 674 |
| AS10310 | Yahoo Holdings Inc. | 661 |
| AS134555 | Encoo Pty Ltd | 578 |
| AS10235 | - | 539 |
| AS56105 | - | 537 |
| AS37978 | - | 534 |
| AS136522 | - | 525 |
| AS59330 | - | 524 |
| AS24316 | - | 522 |
The 30 most visible of 301.
4 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.