On a site that I operate I use several layers of protection for our subscription content. Among the other protections, each content item is placed into a folder with a randomly generated 19-character name. That name can include numbers, lowercase letters, and uppercase letters.
While it will not really lower the benefit provided by this layer of protection for a second file to end up in a folder, I am curious about the chances of that happening. That leads me to two related questions:
- Assuming that we have 2500 files/folders, what is the chance that the next folder we generate will be a repeat?
- How many folders must exist for the chance of repetition to rise above 1%?