On Backlink Explorer, backlinks are calculated in seconds and are displayed according to different parameters such as URL Flow Metrics (Trust Flow and Citation Flow), Domain Flow Metrics (Trust Flow and Citation Flow), Type of link (Dofollow, No-Follow, Deleted) and VIsibility (First Seen, Last Seen and Date Lost).
The backlinks have been distributed on the basis of the following parameters -
Active Vs. Deleted
Do Follow Vs. Nofollow
Image Vs. Text Vs Frame Vs Redirects