List of the top 20 organizations with the largest IP allocations in Czechia
| Rank | Name | IPv4 addresses | IPv6 /64 networks | AS numbers | Prefixes |
|---|---|---|---|---|---|
| Vodafone Czech Republic a.s. | 2,296,832 | 1.44 x 238 | 1 | 110 | |
| O2 Czech Republic, a.s. | 2,242,560 | 1.5 x 235 | 1 | 65 | |
| T-Mobile Czech Republic a.s. | 1,231,104 | 1.31 x 236 | 4 | 54 | |
| 4 | CESNET z.s.p.o. | 857,088 | 1.13 x 235 | 1 | 24 |
| 5 | ALFA TELECOM s.r.o. | 526,848 | 0 | 1 | 11 |
| 6 | PODA a.s. | 335,104 | 1.5 x 233 | 2 | 31 |
| 7 | Nej.cz s.r.o. | 334,848 | 1.53 x 237 | 8 | 64 |
| 8 | CETIN a.s. | 330,496 | 1.13 x 235 | 1 | 11 |
| 9 | Quantcom, a.s. | 275,968 | 234 | 3 | 41 |
| 10 | DHL Information Services (Europe) s.r.o | 217,344 | 1.06 x 222 | 1 | 29 |
| 11 | Nordic Telecom Regional s.r.o. | 183,296 | 1.16 x 237 | 11 | 49 |
| 12 | CD-Telematika a.s. | 118,784 | 232 | 1 | 14 |
| 13 | RADIOKOMUNIKACE a.s. | 106,752 | 232 | 1 | 6 |
| 14 | InterneXt 2000, s.r.o. | 75,776 | 236 | 2 | 13 |
| 15 | Brno University of Technology | 67,840 | 1.63 x 235 | 2 | 14 |
| 16 | Master Internet s.r.o. | 58,880 | 1.31 x 236 | 1 | 46 |
| 17 | STARNET, s.r.o. | 55,808 | 1.56 x 236 | 1 | 25 |
| 18 | ha-vel internet s.r.o. | 53,248 | 232 | 1 | 17 |
| 19 | Ipex Ltd. | 46,080 | 232 | 1 | 6 |
| 20 | INTERNET CZ, a.s. | 45,824 | 232 | 1 | 12 |