Having determined vulnerabilities on your victim's system, you might think you are now ready to launch a full fledged attack. But wait a minute, are you discreet enough? Rushing into a bank to rob it without any masks on will only get you instantly identified and ultimately arrested. Although escape plan usually comes after the attack stage, yet you need to mask your identity as much as possible before even thinking of conducting an attack. This is where proxies come in.
Next on the list of methodologies under Stage 2 - Scanning are Network Scanning and Vulnerability Scanning. I am sure that by now you have a basic idea of how to discover live systems on a network, find open ports on it and fingerprint the services and OS running on it.