It says that NOD32 can stop virus before it enter system. My questions is how is possible to scan something that is not in the system?
The IMON component sets itself up at the network level (kind of like a firewall), so it has the ability to scan your downloads at the network level, before they ever reach the hard drive. IMON can scan HTTP downloads (web browser) and POP3 downloads ("regular" e-mail downloads).