| Date | IP Address |
| 2025-02-04 | 89.191.86.207 (ClassC) |
| 2025-09-08 | 89.191.91.140 (ClassC) |
| 2026-02-20 | 89.191.67.180 (ClassC) |
| Date | Domain | IP |
| pbe.urlaub.check24.at | 2025-09-22 | 89.191.86.207 |
| staging.urlaub.check24.at | 2025-08-20 | 89.191.67.180 |
| m.urlaub.check24.at | 2025-05-22 | 89.191.67.180 |
| integration.urlaub.check24.at | 2025-06-22 | 89.191.67.180 |
| assistant.urlaub.check24.at | 2025-02-04 | 89.191.86.207 |