$(10$ points$)$ A distributed denial$-$of$-$service $($DDoS$)$ is a type of DoS $($denial$-$of$-$service$)$

attack where the traffic used to overwhelm the target is coming from many distributed

sources. This method means the attack can't be stopped just by blocking the source of

traffic. Google some famous real$-$world DDoS, briefly describe two of them. For example,

the GitHub attack in $2018.$