The nature of the Internet makes web applications vulnerable to a number of attacks. Web application security involves using a holistic approach to mitigate attacks.
In a distributed denial-of-service (DDoS) attack, a network of computers work in tandem to overflow an access point and prevent legitimate users from accessing a service.
The domain name system (DNS) is often referred to as a phone book for the internet. it's the worldwide network that connects users to web content via domain names.