🇨🇿 Czechia
Registry and organization country assignments can differ from the physical location of an IP. Snapshot: 2026-10-04.
9,557,952
Delegated IPv4 address slots
724
Registered ASNs
27
Hosting ASNs
868
Known VPN exit prefixes
Country reference
- ISO code
- CZ
- Continent
- Europe
- Capital
- Prague
- Currency
- CZK
- Calling code
- 420
- EU member
- Yes
- Delegated IPv6 address slots
- 244,260,582,191,833,502,702,688,710,688,768
Registry allocations
Allocated and assigned RIR prefixes; address slots are summed across records and may overlap.
| Registry | Prefixes | IPv4 slots | IPv6 slots |
|---|---|---|---|
| ARIN | 7 | 395,264 | 79,228,162,514,264,337,593,543,950,336 |
| RIPE_NCC | 2,461 | 9,162,688 | 244,181,354,029,319,238,365,095,166,738,432 |
Major autonomous systems
Showing up to 200 of 724 ASNs assigned to this country, ranked by announced IPv4 prefix address slots. Overlapping announcements count separately.
| ASN | Organization | Category | IPv4 slots | IPv6 prefixes |
|---|---|---|---|---|
| AS5610 | O2 Czech Republic, a.s. | business | 2,327,808 | 5 |
| AS16019 | Vodafone Czech Republic a.s. | business | 2,295,808 | 17 |
| AS13036 | T-Mobile Czech Republic a.s. | isp | 1,025,024 | 3 |
| AS2852 | CESNET z.s.p.o. | business | 858,880 | 2 |
| AS44546 | ALFA TELECOM s.r.o. | isp | 527,616 | 0 |
| AS2571 | DHL Information Services (Europe) s.r.o | business | 438,784 | 46 |
| AS29208 | Quantcom, a.s. | business | 274,432 | 6 |
| AS28725 | CETIN a.s. | business | 265,472 | 2 |
| AS30764 | PODA a.s. | business | 220,416 | 3 |
| AS42908 | O2 Czech Republic, a.s. | business | 183,296 | 9 |
| AS16246 | O2 Czech Republic, a.s. | business | 133,120 | 2 |
| AS25512 | CD-Telematika a.s. | business | 117,760 | 1 |
| AS15425 | PODA a.s. | business | 110,592 | 1 |
| AS25248 | RADIOKOMUNIKACE a.s. | business | 106,752 | 2 |
| AS44489 | STARNET, s.r.o. | business | 77,312 | 7 |
| AS197451 | Brno University of Technology | education | 67,584 | 4 |
| AS31246 | O2 Czech Republic, a.s. | business | 66,560 | 2 |
| AS24971 | MasterDC s.r.o. | hosting | 58,880 | 13 |
| AS12570 | O2 Czech Republic, a.s. | business | 53,760 | 2 |
| AS41046 | O2 Czech Republic, a.s. | business | 53,248 | 2 |
| AS15935 | ha-vel internet s.r.o. | business | 51,968 | 3 |
| AS24806 | INTERNET CZ, a.s. | hosting | 48,640 | 1 |
| AS6740 | CEZNET s.r.o. | business | 41,984 | 0 |
| AS21430 | WIA spol. s.r.o. | business | 41,472 | 5 |
| AS39906 | CoProSys a.s. | business | 37,888 | 2 |
Largest cities by reference population
GeoNames reference data; this is not a count of located IP addresses.
- Prague · 1,165,581
- Brno · 379,466
- Ostrava · 279,791
- Pilsen · 168,733
- Liberec · 102,951
- Olomouc · 99,496
- České Budějovice · 93,426
- Hradec Králové · 90,596
- Ústí nad Labem · 90,378
- Pardubice · 88,520
Hosting counts use ASN organization classifications. VPN counts include distinct exit prefixes with a source-provided country seen within seven days of this snapshot; zero means no known evidence, not absence. Country and city references: GeoNames (CC BY 4.0).