Layer 4 DDoS attacks refer to attacking the real network.
It requires a lot of bandwidth. Imagine a store and its
customers entering/exiting. We'll say the store is the
host you want to attack and people are the packages you're
sending to the host. What a DDoS does is literally get
everyone quickly, quickly. This makes everything slower
and eventually the store will be unavailable because no
one will be able to enter. Layer 7 DDoS attacks refer to
attacking the application layer of a server. When we say
Layer 7, we are not attacking the network itself, but the
real applications hosted on the network. Generally, when
we talk about Layer 7 attacks, we usually talk about HTTP
DDoS attacks. In the XML-RPC scenario.