AS21557 Cybernet Communications, Inc.

CYB-BLK-1 - Cybernet Communications, Inc. · registered in the United States

IPv4 addresses12,80015 prefixes · <0.001% of announced IPv4

Rank in United States#2,618largest network in US by IPv4 space, of 18,338 · <0.01% of US

Rank worldwide#7,949of 79,396 networks with IPv4

IPv61 x /32 (65,536 x /48)9 prefixes

CountryUnited States18,679 ASNs registered there

Open AS21557 in ASN lookup Look up an IP in this network (23.128.104.1) All networks in United States

IPv4 prefixes

All 15 prefixes, in address order.

23.128.104.0/23
64.15.208.0/21
64.15.216.0/23
64.15.218.0/24
64.15.219.0/24
64.15.220.0/22
75.127.48.0/23
75.127.50.0/23
75.127.52.0/22
75.127.56.0/23
75.127.58.0/23
75.127.60.0/22
104.218.188.0/22
147.92.120.0/21
162.219.200.0/22

IPv6 prefixes

All 9 prefixes.

2605:5300::/39
2605:5300:200::/39
2605:5300:400::/39
2605:5300:600::/39
2605:5300:800::/37
2605:5300:1000::/36
2605:5300:2000::/35
2605:5300:4000::/34
2605:5300:8000::/33

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IP-to-ASN data: iptoasn.com (public domain). Snapshot downloaded 2026-11-11, refreshed daily. Ranges are what each network announces in BGP, not registry allocations. Data sources