If there is one tool that is ubiquitous through most top-tier and new assessor toolkits, it is nmap. You may find different exploitation frameworks, web application tools, and other preferences, but nmap is a staple tool for many forms of assessment. Now, this is not to say that there are no other tools that can be executed with similar capabilities; it's just that they are not as capable. This includes tools such as AngryIP, HPing, FPing, NetScan, Unicorn scan, and others. From all of these tools, only two stand out as significantly different, and they are HPing and Unicorn scan.

The biggest mistake I see new assessors making with nmap is executing more than one scan at a time from the same host. What they do not realize is that nmap uses the integrated TCP/IP stack of the host operating system. This means that any additional scan executed does not speed the results; instead, the multiple sessions must be handled at the same time by the operating systems TCP/IP stack....