DDoS mitigation is a set of techniques or tools for resisting or mitigating the impact of distributed denial-of-service (DDoS) attacks on networks attached to the Internet by protecting the target and relay networks. DDoS attacks are a constant threat to businesses and organizations by threatening service performance or to shut down a website entirely, even for a short time.
After the detection is made, the next process is filtering. Filtering can be done through anti-DDoS technology like connection tracking, IP reputation lists, deep packet inspection, blacklisting/whitelisting, rate limiting. 
One technique is to pass network traffic addressed to a potential target network through high-capacity networks with "traffic scrubbing" filters.
Manual DDoS mitigation is no longer recommended due to DDoS attackers being able to circumvent DDoS mitigation software that is activated manually. Other ways to prevent DDoS attacks can be implemented on-premise or/and via cloud-based solution providers. Through on-premise mitigation the technology (most commonly a hardware device) is placed „in front” of the network, with the disadvantage that the filtering capacity is limited to the capacity of the filtering device. A middle option is to have a hybrid solution by combining on-premise filtering with cloud-base filtering such as Neustar.
Best practices for DDoS mitigation include having both anti-DDoS technology and anti-DDoS emergency response services such as Arbor Networks, Incapsula, Allot, Akamai, CloudFlare or Radware. DDoS mitigation is also available through cloud-based providers such as Verisign and Voxility.
Methods of attack
DDoS attacks are executed against websites and networks of selected victims. A number of vendors are offering "DDoS resistant" hosting services, mostly based on techniques similar to content delivery networks. Distribution avoids single point of congestion and prevents the DDoS attack from concentrating on a single target.
One technique of DDoS attacks is to use misconfigured third-party networks that allow amplification of spoofed UDP packets. Proper configuration of network equipment, enabling ingress filtering and egress filtering, as documented in BCP 38 and RFC 6959, prevents amplification and spoofing, thus reducing the number of relay networks available to attackers.
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