A flood guard protects against Denial of Service (DOS) flooding attacks. A SYN attack or a SYN flood is one example of a DOS flooding attack. ARP spoofing is falsifying ARP responses, typically used to perform a localized man-in-the-middle attack, not a flood. DNS poisoning is used to falsify the IP address received when a fully qualified domain name (FQDN) is resolved. Domain Name System (DNS) poisoning is used in pharming attacks as well as man-in-the-middle attacks, not flooding. MAC hijacking occurs when an attacks spoofs their MAC address as that of someone else, this is not a flooding attack.