A reservation is a feature of DHCP that allows a device with a specific MAC address to be always assigned the same IP address from the DHCP server. A reservation is configured by mapping the MAC address of the device to the desired IP address on the DHCP server. This ensures that the device will always receive the same IP address, regardless of the lease time or the availability of other IP addresses in the DHCP pool. The other options are not features of DHCP that can ensure a device with a specific MAC address is always assigned the same IP address, as they either do not involve MAC addresses, do not guarantee IP address consistency, or do not use DHCP at all. References: CISSP - Certified Information Systems Security Professional, Domain 4.
Communication and Network Security, 4.2 Secure network components, 4.2.1 Establish secure communication channels, 4.2.1.1 Transmission methods; CISSP Exam Outline, Domain 4. Communication and Network Security, 4.2 Secure network components, 4.2.1 Establish secure communication channels,
4.2.1.1 Transmission methods