| Date | IP Address |
| 2026-01-20 | 209.235.125.89 (ClassC) |
| Date | Domain | IP |
| saxonhomeschool.harcourtachieve.com | 2025-05-10 | 44.207.125.31 |
| steckvaughn.harcourtachieve.com | 2025-03-06 | 44.219.204.92 |
| reads.harcourtachieve.com | 2024-11-24 | 54.88.81.136 |
| saxonpublishers.harcourtachieve.com | 2025-04-29 | 34.195.50.209 |
| steckvaughnadult.harcourtachieve.com | 2025-03-25 | 44.205.66.168 |
| www.harcourtachieve.com | 2026-01-20 | 209.235.125.89 |
| rigby.harcourtachieve.com | 2024-11-24 | 54.88.81.136 |