I tried for my first time the fast and capable masscan, which is the best Open Source Network Security Scanner I ever used. It allowed me to scan and map a large IP address space covering over million hosts.
once I identified a specific vulnerable pattern on a machine, I could easily cross reference this pattern with over the millions of discovered hosts in #masscan database.
For more information and to try out the masscan-web-ui for yourself, you can check out the GitHub project page.