What is a key risk when using a fast TCP SYN scanning tool like ScanRand?

• A. It may bypass authentication
• B. It can never crash services
• C. It may cause a denial of service attack
• D. It encrypts traffic

Answer: (C)

When you fire off a fast TCP SYN scan, you’re effectively flooding the target with connection attempts. Each SYN that gets a SYN-ACK and isn’t followed by a full handshake ties up resources for a moment. TCP stacks keep a backlog of half-open connections; if a flood arrives faster than the system can process and clear them, the backlog fills up. That can cause legitimate connections to be dropped or delayed, and in extreme cases bring down or seriously degrade services. So the main risk is that rapid SYN scanning can induce a denial of service on the target. The other options don’t fit: a SYN scan doesn’t bypass authentication, it isn’t true that it can never crash services, and it doesn’t encrypt traffic.