What is the difference between a Layer 3/4 DDoS attack and a Layer 7 DDoS attack, and how does this relate to brute-force attacks?

Layer 3/4 attacks target the network and transport layers (IP addresses, ports, protocols) with high-volume traffic. Layer 7 attacks target the application layer (HTTP requests, etc.), focusing on exhausting server resources with seemingly legitimate requests. Brute-force DDoS attacks are typically Layer 7 attacks, as they involve sending a high rate of application-level requests designed to overwhelm the server's processing capacity.