AS2852 CESNET z.s.p.o.

Czechia CESNET2 RIPE 26 IPv4 prefixes 1 IPv6 prefix

IPv4 addresses

849,920

IPv6 /48 networks

524,288

RPKI

27 valid0 no ROA

Peers and downstreams

168

Holder

AS name: CESNET2
Description: CESNET z.s.p.o.
Organisation: CESNET z.s.p.o.
Registered in: Dejvice, Czechia
Abuse contact: abuse@cesnet.cz
Assigned: 1993-12-19
Registered: 2002-06-22
Record last changed: 2026-09-13 21:22 UTC

AS553	Belwue BELWUE
AS559	SWITCH Switch
AS1031	PEER 1031 LLC PEER1-1031
AS1140	Stichting Internet Domeinregistratie Nederland SIDN
AS1764	Next Layer Telekommunikationsdienstleistungs- und Beratungs GmbH NEXTLAYER-AS
AS1828	Unitas Global UNITAS
AS1836	green.ch AG GREEN
AS2607	Zdruzenie pouzivatelov Slovenskej akademickej datovej siete SANET SANET
AS3212	Telemach Slovenija d.o.o. TELEMACH
AS3214	xTom GmbH XTOM
AS3333	Reseaux IP Europeens Network Coordination Centre (RIPE NCC) RIPE-NCC-AS
AS4230	CLARO S.A. AS4230
AS4455	IX Reach Ltd BSO
AS5405	Inter.link GmbH INTERDOTLINK
AS6057	Administracion Nacional de Telecomunicaciones AS6057
AS6204	TMRC GROUP SRL ZET-NET
AS6424	EDGOO NETWORKS UNIPESSOAL LDA EDGOO
AS6461	Zayo Bandwidth ZAYO-6461
AS6663	Euroweb Romania S.R.L. TTI-NET
AS6667	Elisa Oyj EUNET-FINLAND
AS6695	DE-CIX Management GmbH DECIX-AS
AS6777	Amsterdam Internet Exchange B.V. AMS-IX-RS
AS6797	GlobalConnect AB GLOBALCONNECT-NET
AS6881	NIX.CZ z.s.p.o. NIXCZ
AS7195	EDGEUNO S.A.S AS7195
AS7713	PT Telekomunikasi Indonesia telkomnet-as-ap
AS8218	Zayo Infrastructure France SA NEO-ASN
AS8298	IPng Networks GmbH IPNG
AS8529	Zain Omantel International FZ-LLC OMANTEL-AS
AS8758	Iway AG IWAY
AS8888	xTom Pty Ltd XTOM
AS9044	BSE Software GmbH SOLNET
AS12577	MMC GmbH MMC-AT-AS
AS12637	SEEWEB s.r.l. SEEWEB
AS12779	IT.Gate S.p.A. ITGATE
AS12859	BIT BV NL-BIT
AS12969	Ljosleidarinn ehf Vodafone_Iceland
AS13030	Init7 (Switzerland) Ltd. INIT7
AS13237	euNetworks GmbH LAMBDANET-AS
AS14630	Invesco Group Services, Inc. INVESCO
AS14840	BR.Digital Telecom AS14840
AS14907	Wikimedia Foundation Inc. WIKIMEDIA
AS15547	netplus.ch SA NETPLUS
AS15605	Connesi s.p.a. CONNESI
AS15802	Emirates Integrated Telecommunications Company PJSC DU-AS1
AS15958	CETIN Ltd. Belgrade CETIN_doo_AS
AS17639	Converge ICT Solutions Inc. CONVERGE-AS
AS18106	Viewqwest Pte Ltd VIEWQWEST-SG-AP
AS20326	TeraSwitch Networks Inc. TERASWITCH
AS20485	Joint Stock Company TransTeleCom TRANSTELECOM
AS20562	Broadband Hosting B.V. OPEN-PEERING-AS
AS20723	AVONET, s.r.o. MGI
AS20764	CJSC RASCOM RASCOM-AS
AS20766	Association "Gitoyen" GITOYEN-MAIN-AS
AS20932	Services Industriels de Geneve SIG-ST
AS20965	GEANT Vereniging GEANT
AS21412	UAB "Cgates" CGATES-AS
AS22356	Durand do Brasil Ltda AS22356
AS24482	SG.GS SGGS-AS-AP
AS24889	Monzoon Networks AG MONZOON-AS
AS24961	WIIT AG MYLOC-AS
AS25091	IP-Max SA IP-Max
AS25160	Vorboss Limited VORBOSS
AS25220	equada network GmbH GLOBALNOC-AS
AS28716	Retelit Digital Services S.p.A. RETELIT-AS
AS28917	Fiord Networks, UAB Fiord-AS
AS29075	IELO-LIAZO SERVICES SAS IELO
AS29140	Hostserver GmbH HOSTSERVER-AS
AS29504	Freenet Liberec, z.s. LBCFREE
AS29632	Netassist International EOOD NASSIST-AS
AS29691	Nine Internet Solutions AG NINE
AS30844	Liquid Telecommunications Ltd LIQUID-AS
AS31510	Innsbrucker Kommunalbetriebe AG IKB-AS
AS33891	Core-Backbone GmbH CORE-BACKBONE
AS34019	Hivane Association HIVANE
AS34177	Celeste SAS CELESTE-AS
AS34288	Kantonsschule Zug AS34288
AS34549	meerfarbig GmbH & Co. KG MEER-AS
AS34927	iFog GmbH iFog-GmbH
AS35280	F5 Networks SARL F5
AS35360	Gargunet GARGUNET
AS35625	Eurofiber France SAS EUROFIBER-FRANCE
AS36236	NetActuate, Inc NETACTUATE
AS37100	SEACOM Limited
AS37468	Angola Cables
AS37497	Network Platforms (PTY) LTD
AS37721	Virtual Technologies & Solutions
AS39120	Convergenze S.p.A. CONVERGENZE-AS
AS39122	Blacknight Internet Solutions Limited BLACKNIGHT-AS
AS39249	Netassist International EOOD KICUA-AS
AS39351	31173 Services AB ESAB-AS
AS40994	Hohl IT e.U. Alwyzon
AS41327	Fiber Telecom S.p.A. FIBERTELECOM-AS
AS42541	Fiberby ApS FIBERBY
AS44901	Belcloud LTD belcloud
AS45489	Sri Lanka Telecom PLC, GLobal Peering SLT-GLOBAL
AS47147	Anexia Cloud Solutions GmbH AS-ANX
AS47692	Nessus GmbH NESSUS
AS48185	team.blue NV team_blue
AS48362	Tkswf TKSWF-AS
AS48919	UACITY Ltd. UA-CITY-AS
AS49544	i3D.net B.V i3Dnet
AS49605	Digital Telecommunication Services S.r.l. DTS-AS
AS50300	CustodianDC Limited CUSTDC
AS50673	Serverius Holding B.V. Serverius-as
AS50763	Robert McKay MCKAYCOM
AS51184	Fonira Telekom GmbH FONIRA
AS51185	MainStreaming SpA MAINSTREAMING-AS
AS51873	Arcade Solutions AG AS-ARCADE
AS56662	Eutpnet EUTPNET
AS56987	ABACLOUDA SAS AS-ABACLOUDA
AS57777	Jeroen Massar MASSAR
AS58057	Securebit AG SECUREBIT
AS58299	Openfactory GmbH OPENFACTORY-AS
AS60171	AFR-IX TELECOM S.A. AFRIX-AS
AS61049	Exascale Ltd EXASCALE
AS61573	IP TELECOM AS61573
AS64475	Freifunk Frankfurt am Main e.V. FREIFUNK-FRANKFURT
AS137409	GSL Networks Pty LTD GSLNETWORKS-AS-AP
AS142271	EWS DS Networks Inc DOUBLESQUARE-AS-AP
AS198150	SIACOM JSC SIACOM-AS
AS198249	Ops One AG OPSONE
AS198385	AlpineDC SA AlpineDC
AS199524	G-Core Labs S.A. GCORE
AS199938	Netzwerge GmbH NETZWERGE
AS202297	Skylon Solutions Limited SKYLON
AS205112	PHILUNET GmbH PHILUNET
AS206356	Freifunk Essen e.V. Freifunk-Essen
AS209823	Enki Multimedia EURL ENKI-AS
AS210937	Showfom
AS212024	Risson RISSON
AS212483	LEVEL EIGHTY-SIX COMMUNICATIONS LTD level86
AS212635	Jurrian van Iersel AS212635
AS213151	Christian Elsen CHRISELSEN
AS213241	TECHIT.BE SRL TECHIT
AS263152	MIGO TELECOM AS263152
AS263444	Open X Tecnologia Ltda AS263444
AS264409	Huge Solucoes Corporativas Ltda AS264409
AS264479	Turbozone Internet AS264479
AS271253	LINK BRASIL TELECOMUNICACOES LTDA AS271253

Upstream graph

Upstreams and their upstreams, from BGP paths

Network health

Grade A · 90/100

pass	Prefixes covered by valid ROAs 27 of 27 announced prefixes are RPKI valid.	25/25
pass	No RPKI invalid announcements None of the announcements is RPKI invalid.	10/10
pass	Announces IPv6 1 IPv6 prefix.	15/15
pass	More than one upstream 5 upstreams seen in BGP.	10/10
pass	Working abuse contact abuse@cesnet.cz is published.	15/15
fail	Publishes a geofeed No geofeed found. Without one, location databases have to guess.	0/10
pass	No prefixes smaller than /24 or /48 All prefixes are /24 (IPv4) or /48 (IPv6) or larger.	10/10
pass	Registry record maintained Last changed 2026-09-13.	5/5

Built from the announced prefixes, RPKI, the registry record and geofeeds. Checks without data are not counted. Also in the API.

Show this on your website

HTML

<a href="https://ip-fd.net/asn/2852"><img src="https://ip-fd.net/badge/asn/2852/health.svg" alt="AS2852 network health on IP-FD.net"></a>

Markdown

[![AS2852 network health](https://ip-fd.net/badge/asn/2852/health.svg)](https://ip-fd.net/asn/2852)

Use rpki.svg instead of health.svg for the RPKI badge.

Routing changes

Last 30 days

2026-10-04 07:18 UTC	Neighbour gone	AS205103	upstream
2026-10-04 07:18 UTC	Neighbour gone	AS52320	peer
2026-10-04 07:18 UTC	Neighbour gone	AS35710	peer
2026-10-04 07:18 UTC	Neighbour gone	AS31027	peer
2026-10-04 07:18 UTC	Neighbour gone	AS4601	upstream
2026-10-04 07:18 UTC	Neighbour gone	AS1267	upstream
2026-10-04 07:18 UTC	New neighbour	AS8888	peer
2026-10-04 07:18 UTC	New neighbour	AS264479	peer
2026-10-04 07:18 UTC	New neighbour	AS203165	downstream
2026-10-04 07:18 UTC	Relationship changed	AS9044	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS8758	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS8298	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS8218	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS7713	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS7195	upstream to peer
2026-10-04 07:18 UTC	New neighbour	AS6797	peer
2026-10-04 07:18 UTC	Relationship changed	AS6777	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS6695	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS6663	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS6204	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS61049	upstream to peer
2026-10-04 07:18 UTC	New neighbour	AS6057	peer
2026-10-04 07:18 UTC	Relationship changed	AS60171	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS5405	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS50673	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS48362	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS47147	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS4455	upstream to peer
2026-10-04 07:18 UTC	New neighbour	AS4230	peer
2026-10-04 07:18 UTC	Relationship changed	AS41327	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS39351	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS39249	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS39120	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS37497	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS37468	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS37100	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS35625	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS35280	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS34927	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS34549	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS34177	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS34019	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS33891	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS30844	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS29691	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS29632	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS29075	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS28716	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS264409	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS263444	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS24961	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS24889	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS22356	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS212024	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS20965	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS20766	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS20764	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS20723	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS20562	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS20485	upstream to peer
2026-10-04 07:18 UTC	New neighbour	AS20326	peer
2026-10-04 07:18 UTC	Relationship changed	AS1836	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS1764	upstream to peer
2026-10-04 07:18 UTC	New neighbour	AS174	upstream
2026-10-04 07:18 UTC	Relationship changed	AS15958	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS15802	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS14840	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS137409	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS13030	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS12859	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS12779	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS12577	upstream to peer
2026-10-04 07:18 UTC	Relationship changed	AS1031	upstream to peer

WHOIS

aut-num:        AS2852
as-name:        CESNET2
org:            ORG-CA9-RIPE
remarks:        Transit networks
remarks:        --------------------------
remarks:        GEANT_IAS_VRF
remarks:        --------------------------
remarks:        CBF peerings
remarks:        --------------------------
remarks:        GEANT connection
remarks:        --------------------------
remarks:        --------------------------
remarks:        AMS-IX peerings
remarks:        ColocationIX GmbH
remarks:        Packet Clearing House
remarks:        CCBill
remarks:        Telenor
remarks:        BBC
remarks:        NTT Communications
remarks:        Golden telecom Moscow
remarks:        RUNNET
remarks:        Swisscom/IP-Plus
remarks:        Packet Clearing House - peer
remarks:        Virgin Media
remarks:        Euronet NL
remarks:        Atrato IP Networks
remarks:        Atrato IP Networks - IPv6
remarks:        Shaw Cablesystems
remarks:        EPT-LU
remarks:        Euroweb Romania SA
remarks:        EunetIP
remarks:        EunetIP - IPv6
remarks:        Belgacom-ICS
remarks:        Belgacom-ICS IPv6
remarks:        Telefonica Deutschland
remarks:        Hurricane Electric, CA
remarks:        Hurricane Electric, CA IPv6
remarks:        Microsoft
remarks:        Viatel
remarks:        NEOT
remarks:        NEOT IPv6
remarks:        COMSTAR
remarks:        COMSTAR IPv6
remarks:        MANDA
remarks:        MANDA IPv6
remarks:        Belgian Network Solution
remarks:        Belgian Network Solution IPv6
remarks:        ENTANET
remarks:        ENTANET IPv6
remarks:        OBIT
remarks:        Kingston Communications
remarks:        Kingston Communications IPv6
remarks:        EMIX
remarks:        @Home
remarks:        InterConnect Services BV
remarks:        InterConnect Services BV IPv6
remarks:        Yahoo
remarks:        Yahoo IPv6
remarks:        SOLCON
remarks:        SOLCON IPv6
remarks:        WideXS
remarks:        WideXS IPv6
remarks:        NL-CONCEPTS
remarks:        NL_CONCEPTS IPv6
remarks:        Highwinds Network Group, Inc.
remarks:        Highwinds Network Group, Inc. IPv6
remarks:        Init Seven AG
remarks:        Init Seven AG IPv6
remarks:        Tele2 NL
remarks:        City-Guide Internet Services
remarks:        City-Guide Internet Services IPv6
remarks:        EdgeCast networks
remarks:        Google Inc.
remarks:        Google Inc. IPv6
remarks:        Allstream Corp.
remarks:        ZeelandNet BV
remarks:        Neuf Telecom
remarks:        TrueServer BV
remarks:        IS Internet Services BV
remarks:        IS Internet Services BV IPv6
remarks:        GrafiX Internet B.V.
remarks:        GrafiX Internet B.V. IPv6
remarks:        Rix|Port80
remarks:        Rix|Port80 IPv6
remarks:        OVH
remarks:        WV Fiber
remarks:        WV Fiber IPv6
remarks:        Griffin
remarks:        Akamai Technologies EU
remarks:        Akamai Technologies Mapping AS
remarks:        Limelight Networks
remarks:        Terremark
remarks:        ASGCNet
remarks:        ASGCNet IPv6
remarks:        Caveo Internet BV
remarks:        Caveo Internet BV IPv6
remarks:        Netholding NL
remarks:        Publieke Omroep
remarks:        NEDZONE
remarks:        CAMBRIUM BV.
remarks:        CAMBRIUM BV. IPv6
remarks:        Routit B.V.
remarks:        Zen Systems
remarks:        Zen Systems IPv6
remarks:        UnilogicNet
remarks:        UnilogicNet IPv6
remarks:        Signet BV
remarks:        Signet BV IPv6
remarks:        Citytelecom.ru
remarks:        UNET
remarks:        Evolva Telecom
remarks:        Evolva Telecom IPv6
remarks:        Duocast B.V.
remarks:        Etelecom.ru
remarks:        DENIC eG
remarks:        DENIC eG IPv6
remarks:        COMX.DK
remarks:        EuroTransit GmbH
remarks:        Euroaccess Enterprises
remarks:        Vodafone
remarks:        Vodafone IPv6
remarks:        Docler Networks
remarks:        Verisign
remarks:        Easyhosting.nl
remarks:        Easyhosting.nl. IPv6
remarks:        Netlogics BV
remarks:        Netlogics BV IPv6
remarks:        Anders.ru
remarks:        Anders.ru IPv6
remarks:        IPTP
remarks:        Net Ground B.V.
remarks:        Opencarrier.eu
remarks:        Opencarrier.eu IPv6
remarks:        LocalPhone Ltd. UK
remarks:        NForce Entertainment BV
remarks:        Hispaweb-Network
remarks:        Transit Data Hyper Network
remarks:        INTERFIBER
remarks:        Xtra Media Services
remarks:        IC-Hosting
remarks:        Pictura Database Publishing
remarks:        Peerings at NIX.CZ
remarks:        --------------------------
remarks:        CESNET2 Members
remarks:        --------------------------
admin-c:        VN2-RIPE
tech-c:         VN2-RIPE
status:         ASSIGNED
mnt-by:         RIPE-NCC-END-MNT
mnt-by:         AS2852-MNT
created:        2002-06-22T23:41:57Z
last-modified:  2026-09-13T21:22:38Z
source:         RIPE
% 585 routing policy lines (import/export) not shown

Routing data

Updated 12 h ago

Registry record

Fetched 12 h ago from RIPE

Prefixes and neighbours come from the RIPE RIS route collectors. Data older than 5 minutes is refreshed when this page is opened.

API

curl -H "X-API-Key: YOUR_KEY" https://ip-fd.net/api/v1/asn/2852

const res = await fetch('https://ip-fd.net/api/v1/asn/2852', {
  headers: { 'X-API-Key': 'YOUR_KEY' }
});
const data = await res.json();
console.log(data);

import requests

r = requests.get('https://ip-fd.net/api/v1/asn/2852', headers={'X-API-Key': 'YOUR_KEY'}, timeout=10)
r.raise_for_status()
print(r.json())

<?php
$ch = curl_init('https://ip-fd.net/api/v1/asn/2852');
curl_setopt($ch, CURLOPT_HTTPHEADER, ['X-API-Key: YOUR_KEY']);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$data = json_decode(curl_exec($ch), true);
print_r($data);

req, _ := http.NewRequest("GET", "https://ip-fd.net/api/v1/asn/2852", nil)
req.Header.Set("X-API-Key", "YOUR_KEY")
res, err := http.DefaultClient.Do(req)
if err != nil {
    log.Fatal(err)
}
defer res.Body.Close()
body, _ := io.ReadAll(res.Body)
fmt.Println(string(body))

Works without a key at a lower rate. Get a free key.

AS174
AS1853	ACONET ACOnet
AS6939	Hurricane Electric LLC HURRICANE
AS21320	GEANT Vereniging GEANT_IAS_VRF
AS60606	PRO-ZETA a.s. Blindspot

AS702	Uunet UUNET
AS1853	ACONET ACOnet
AS2607	Zdruzenie pouzivatelov Slovenskej akademickej datovej siete SANET SANET
AS2686	AT&T Enterprises, LLC ATGS-MMD-AS
AS5610	O2 Czech Republic, a.s. O2-CZECH-REPUBLIC
AS6461	Zayo Bandwidth ZAYO-6461
AS6855	Slovak Telekom, a.s. SK-TELEKOM
AS16019	Vodafone Czech Republic a.s. VODAFONE-CZ-AS
AS16509	Amazon.com, Inc. AMAZON-02
AS34080	MIRAMO spol. s.r.o. MIRAMO-AS
AS48091	ROWANet ROWANet-AS
AS51727	Doosan Skoda Power s.r.o SKODAPOWER-AS
AS61110	Sprava informacnich technologii mesta Plzne, p.o. SITMP
AS197277	State Institute for Drug Control SUKL_AS
AS197451	Brno University of Technology VUTBR-AS
AS198500	Ustav vypocetni techniky MUNINET-AS Masarykova univerzita
AS199604	OLOMOUCKY KRAJ KU-AS
AS199711	National Cyber and Information Security Agency NCISA-AS
AS200874	Liberecky kraj LBC-AS-CZ
AS201648	Plzensky kraj PLZ-AS-CZ
AS202874	Zl-As-Cz ZL-AS-CZ
AS203165	Statni pokladna Centrum sdilenych sluzeb, s.p. SPCSS
AS204772	Reditelstvi silnic a dalnic s.p. RSD-CZ
AS208093	Moravskoslezsky kraj msk
AS210367	Krajska zdravotni, a.s. KZCR
AS210498	Kraj Vysocina Vysocina-hSOC
AS212876	Pardubicky Kraj CZ-PARDUBICKYKRAJ
AS213152	Narodni bezpecnostni urad Czech Republic NBU