What is a Distributed Denial Of Service attack?
A distributed denial-of-service (DDoS) attack occurs when multiple systems flood the bandwidth or resources of a targeted system, usually one or more web servers. Such an attack is often the result of multiple compromised systems (for example a botnet) flooding the targeted system with traffic. (source Wikipedia)
In this case , there are multiple external sources attacking a web server attached to the network. These attacks can be difficult to pinpoint and can take some time to block completely. Quite often network engineers have to work with upstream providers to block the source of the attacks and this can cause further delays.
