In the context of TCP-based DoS, which statement is true about half-open attacks and border firewalls?

• A. They require encryption.
• B. True
• C. False
• D. Only on internal networks

Answer: (B)

Half-open TCP attacks flood a server with incomplete handshakes (SYN requests that aren’t completed), which ties up memory and the backlog and can exhaust resources. A border firewall sits at the network edge and can cut this off before it reaches the target, using techniques like SYN cookies, rate-limiting, and dropping or throttling suspicious SYN packets. This kind of edge filtering provides protection without needing encryption and is relevant to services exposed to external networks, not just internal ones. So the statement about border firewalls mitigating half-open TCP DoS attacks is true.