Autonomous System

AS57728 CEZNET s.r.o.

ISPActiveCzechiaRIPE

AS57728 (CEZNET-AS) is an ISP network operated by CEZNET s.r.o. in Czechia, registered with RIPE. It has 5 IPv4 prefixes with 15,360 addresses and 3 IPv6 prefixes, which makes it the 8,146th largest of 82,200 active autonomous systems by IPv4 space.

IPv4 addresses15,360in 5 prefixes
IPv6 prefixes3≈ 2.4 × 10²⁹ addresses
Size rank#8,146of 82,200 active ASNs
Abuser scoreLow0.16% of its addresses flagged · method

Details

OrganizationCEZNET s.r.o.
AS nameCEZNET-AS
Websitecogentco.com
Country Czechia (CZ)
Network typeISP
RegistryRIPE
Abuse contactdohled@ceznet.cz
Registered2019-10-21
Last updated2025-09-26

IPv4 prefixes

5 prefixes · 15,360 addresses
NetworkAddressesFirst – last address
188.122.192.0/198,192188.122.192.0 – 188.122.223.255
81.25.16.0/212,04881.25.16.0 – 81.25.23.255
81.25.24.0/212,04881.25.24.0 – 81.25.31.255
109.234.40.0/212,048109.234.40.0 – 109.234.47.255
185.255.116.0/221,024185.255.116.0 – 185.255.119.255

IPv6 prefixes

3 prefixes
  • 2a00:1800::/32
  • 2a00:1807::/32
  • 2a0a:b6c0::/32

Query AS57728 with the API

The ASN lookup returns everything on this page as JSON, including every prefix. ASN lookups need an API key: a free account comes with 1,000 requests a day. 

curl "https://api.ipapi.is/?q=AS57728&key=YOUR_API_KEY"

Any address in its prefixes resolves to AS57728, with or without a key:

curl "https://api.ipapi.is/?q=188.122.192.1"

Other networks of CEZNET s.r.o.

AS6740 CEZNET s.r.o.41,984 IPv4 addressesAS25424 CEZNET s.r.o.33,792 IPv4 addressesAS49101 CEZNET s.r.o.16,384 IPv4 addresses

Largest networks in Czechia

AS5610 O2 Czech Republic, a.s.2,327,808 IPv4 addressesAS16019 Vodafone Czech Republic a.s.1,210,368 IPv4 addressesAS13036 T-Mobile Czech Republic a.s.992,256 IPv4 addressesAS2852 CESNET z.s.p.o.858,112 IPv4 addressesAS44546 ALFA TELECOM s.r.o.527,616 IPv4 addressesAS2571 DHL Information Services (Europe) s.r.o438,528 IPv4 addresses