Detecting the operating system

What is the process of detecting the operating system of a remote computer called? a. OS detection b. OS scanning c. OS fingerprinting d. OS assessment What are the common techniques for determining a remote computer’s operating system? [Choose all that apply.] a. Send specially crafted network packets and examine the responses. b. Send a message asking what the operating system is. c. Send a network packet, ignore the responses, and then evaluate the way the target handles retransmitted packets. d. Read all packets sent by the target computer until an informative packet is found.