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Autonomous System

AS21738 ยท Rozint

Overview

AS21738 is announced on the Internet: RIPE RIS route collectors currently see 8 IPv4 prefixes and 6 IPv6 prefixes originated by this network. Together, its IPv4 prefixes cover 2,816 addresses, with overlapping prefixes counted once. In the paths the collectors record, it has 7 upstream neighbours (transit providers or peers) and 30 downstream neighbours (customers or networks it carries). Its most visible upstreams are Hurricane Electric LLC (AS6939), WholeSale Internet, Inc. (AS32097), and Arelion Sweden AB (AS1299). AS21738 was assigned by ARIN, and its registration country is United States.

Source: RIPEstat (RIPE NCC), RIS route collectors. Read on October 16, 2026 at 10:58 PM UTC. This page is refreshed at most every 12 hours.

Go further

The trace goes to 216.40.92.1, the first address of 216.40.92.0/22. 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 (8 prefixes)

PrefixAddresses
2.59.255.0/24256
23.150.40.0/24256
23.150.41.0/24256
23.160.200.0/24256
43.255.189.0/24256
140.235.156.0/24256
185.125.142.0/24256
216.40.92.0/221,024

IPv6 prefixes (6 prefixes)

Prefix
2602:2b7:40::/48
2602:2b7:c8::/48
2602:2b7:e1::/48
2602:2b7:600::/48
2602:2b7:c00::/40
2602:2b7:d00::/40

Neighbours

Upstreams (transit or peers) (7)

ASNetworkVisibility
AS6939Hurricane Electric LLC4,686
AS32097WholeSale Internet, Inc.3,460
AS1299Arelion Sweden AB301
AS3257GTT Communications Inc.125
AS32621Twin City VoIP, Inc.20
AS52025ParadoxNetworks Limited5
AS286GTT Communications Inc.4

Downstreams (customers) (30)

ASNetworkVisibility
AS212895Johannes Ernst701
AS6517LAKENETWORKS534
AS151349Yuki Network Ltd488
AS401710CloudMesh Labs LLC488
AS402247flew llc484
AS14923Graham Technology Solutions LLC476
AS53388Tefexia LC476
AS30690Kazehana Networks LLC266
AS30114Decima LLC260
AS400451Curium Technologies258
AS270142-251
AS26006-247
AS54148-243
AS216242-241
AS214430-240
AS399542-240
AS216052-239
AS54852-238
AS200160-236
AS202340-233
AS200242-216
AS23459-213
AS207852-205
AS213880-185
AS396962-128
AS216107-40
AS58057Securebit AG3
AS47689Pudu Pudu, LLC2
AS200690-2
AS210250-1

5 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.