A Recycled IP Address Caused Me to Pirate Books by Accident
This is known as "subdomain takeover" and is definitely a common problem. It's probably one of the most frequently reported bug types on hackerone.<p>I wonder -- has anyone written code to spin up EC2 instances and check for subdomains pointing to the IP? Not sure how you could do that efficiently (does rdns work after the IP has been recycled?), but a starting point might be gathering as many NXDOMAIN subdomains as possible, filtering the ones at cloud providers, and starting instances until you get a match.