Why DDoS Hard to Defend

There are many factors due to which DDoS attacks is more cumbersome to defend. One of the first reason is it is simple to initiate. There are variety of tools to generate DDoS traffic, only need to download and install these tools. To make DDoS attack more well-formed legitimate traffic can be generated to attack on a specific application or protocol which looks legitimate but consisted on fake packets to consume the bandwidth of the network. IP Spoofing is a major hurdle for defensive mechanism and botnets makes it more clumsy to defend. It can be initiated for short time span to avoid detection   but makes heavy impact on the victim machine.