I had issues at work with some IPs that fall into an IP wildcard range that was in my denyhots whitelist being blocked by denyhosts. It turns out they were Class B networks and denyhosts wildcard white listing only accepts Class C networks. Although written incorrectly here you undestand what it is saying. The examples do only show Class C networks, but it doesn't explicitly say it ONLY accepts Class C networks, hence why it was hard for me to troubleshoot this issue.