Uncommon load question: many packets from one IP

[NTPman]

May be your NTP server encountered a FortiGate firewall, or some other simmilarly buggy NTP client?

NTP bursts from FortiGate firewalls

(This summarizes a problem mentioned in other discussions.) A recent enhancement to FortiOS, used in the FortiGate firewall, did not handle NTP DNS changes correctly. When DNS mapping changed FortiGate firewalls sent 10 second duration NTP bursts at rates that could exceed 20,000 requests/second. NTP Pool servers were impacted due to the use of DNS load balancing. Our team monitored three NTP pool servers and detected over 150 FortiGate devices sending NTP bursts. FortiGate support identified…