Final answer:
The ISP can divide its address block into four equal-sized address blocks using subnetting. Each organization will be allocated one of these blocks with a specific address range and subnet mask.
Step-by-step explanation:
The ISP has been allocated the address block 200.23.16.0/21. In order to divide this address block into four equal-sized address blocks, the ISP can use subnetting. Each organization will be allocated one of these four address blocks. To determine the address range for each organization, we need to divide the available IP addresses equally among the four blocks. Each block will have 512 IP addresses (2^9).
The address range and subnet mask for each organization will be:
- Organization 1: Address Range: 200.23.16.0 - 200.23.16.127, Subnet Mask: 255.255.255.128
- Organization 2: Address Range: 200.23.16.128 - 200.23.16.255, Subnet Mask: 255.255.255.128
- Organization 3: Address Range: 200.23.17.0 - 200.23.17.127, Subnet Mask: 255.255.255.128
- Organization 4: Address Range: 200.23.17.128 - 200.23.17.255, Subnet Mask: 255.255.255.128