Troubleshooting : Solutions by issue type : Resource issues : DoS attacks
 
DoS attacks
A prolonged denial of service (DoS) can bring your servers down if your FortiADC appliance and your network devices are not configured to prevent it. To prevent DoS attacks, enable the DoS and connection limit features. Also, configure protections on your FortiGate and other network devices. DoS attacks can use a variety of mechanisms. For in-depth protection against a wide variety of DoS attacks, you can use a specialized appliance such as FortiDDoS.
In the web UI, you can watch for attacks in two ways:
Monitor current traffic on the dashboard. Go to System >  Dashboard and examine the system-wide throughput.
Examine attack history in the traffic log. Go to Logs & Report >  Log Browsing >  Security Log.