Regarding server load balancing, which of the following technologies can be used to sense changes in server status and ensure that user requests will not be sent to faulty servers?

Regarding server load balancing, which of the following technologies can be used to sense changes in server status and ensure that user requests will not be sent to faulty servers?
A . VGMP Hello message
B . VRRP packets
C . DPD
D . Service Health Check

Answer: D