Which statement best describes the use of VLSM?

• A. It allows subnets of different sizes to optimize address usage.
• B. It requires all subnets to be the same size.
• C. It eliminates the need for IP addressing planning.
• D. It increases broadcast domains.

Answer: (A)

Variable Length Subnet Masking lets you carve a single network into subnets of different sizes by applying different subnet masks to each one. This matches each subnet to the exact number of hosts required, so you don’t waste address space. For example, a network might need subnets for 14, 60, and 200 hosts. You could use a /28 for the 14‑host subnet, a /26 for the 60‑host subnet, and a /24 for the 200‑host subnet. Fixed-size subnetting would force all subnets to use the same mask, leading to wasted addresses or insufficient space.

VLSM doesn’t eliminate IP address planning—you still need to design the addressing scheme carefully—and it doesn’t inherently increase broadcast domains—the number of broadcast domains is determined by how many subnets you create and how you connect them, not by VLSM itself.

So, the statement that best describes VLSM is that it allows subnets of different sizes to optimize address usage.