A SYN flood attack is when:
A.
A target machine is flooded with TCP connection requests with randomized source address & ports for the TCP ports.
B.
A target machine is sent a TCP SYN packet (a connection initiation), giving the target host’s address as both source and destination, and is using the same port on the target host as both source and destination.
C.
A TCP packet is received with the FIN bit set but with no ACK bit set in the flags field.
D.
A TCP packet is received with both the SYN and the FIN bits set in the flags field.