As you have probably noticed throughout the book, more information is almost always better when running scans. Fortunately, Nmap developers allow us to quickly and easily retrieve information about a scan while it's running, by starting the scan with increased verbosity.
Verbosity lets timing, parallelism, and internal debugging information to display straight to the console while scans run. This can be great to figure out when we need to try to optimize scans in one of the several ways (which we'll learn about in the next chapter). When running a scan in increased verbosity, you can also hit Enter to see how far the scan has progressed, and how far it has to go before completing its current target file. There are several different levels of verbosity, but I usually use the third-level.
The first level of verbosity gives a very basic information about a scan's progress, and can be invoked by using the -v
flag. The second level of verbosity gives more information...