CompTIA Network+ Practice Test

What does VLSM allow network administrators to do?

1. Define their own network protocols

2. Use the same subnet mask across all devices

3. Customize subnet masks to meet specific requirements

4. Limit the number of subnets in a classful network

The correct answer is: Customize subnet masks to meet specific requirements

VLSM, or Variable Length Subnet Masking, enables network administrators to customize subnet masks based on the specific needs of different subnets within the same network. This capability is crucial for optimizing IP address allocation and improving network efficiency. By allowing varying lengths of subnet masks, VLSM helps in creating subnets that can accommodate different numbers of hosts, thereby minimizing waste of IP addresses. For instance, an organization may have several departments that require different numbers of IP addresses. One department may need a small subnet for just a few devices, while another may require a larger subnet for many users. With VLSM, administrators can allocate a subnet mask that meets the specific requirements of each department rather than using a single, uniform subnet mask across the entire network, which could either lead to wasted addresses or insufficient IPs for high-demand areas. The other options do not accurately describe the purpose of VLSM. Defining network protocols is unrelated to subnetting, using the same subnet mask for all devices contradicts the principle of VLSM, and limiting the number of subnets in a classful network does not align with the flexibility that VLSM provides.