

DDOS is a symptom. A DDOS can cause different failure scenarios at different points.
Maybe the attack is causing the service to access a backend database that isn’t equipped to handle the traffic. The web server queues requests but they can’t be handled in a timely manner.
Maybe the attack causes a firewall to spend too much time inspecting the traffic by sending a malformed packet.
Maybe the attack simply overwhelms the bandwidth of the firewall or router. The Reddit “hug of death” is a common example.
In short, lots of things can lead to a service interruption. A DDOS is just a description of a way to cause that interruption by using distributed source hosts.








When a post to a website gets popular but the website doesn’t have enough resources to handle the number of people visiting it.