Final answer:
MAC address-based access control is weak because MAC addresses can be spoofed by attackers, allowing them unauthorized network access, and it does not involve encryption to protect data.
Step-by-step explanation:
Access control based on the MAC address of systems on a network does not represent strong security because MAC addresses can be easily spoofed. This means that an attacker can mimic the MAC address of an authorized device and gain access to the network. While MAC addresses are indeed unique and unchangeable identifiers assigned to network interfaces, this property does not prevent them from being duplicated by malicious software. Moreover, relying solely on MAC addresses for network security does not involve any form of encryption, which is essential for protecting data in transit and ensuring that even if access is gained, the information cannot be easily understood or used by an unauthorized party.