Question

A network administrator has been allocated the block 172.20.0.0/16 and needs to create a subnet that can accommodate at least 500 host addresses while wasting the fewest possible addresses using VLSM. Which subnet mask should be used for this specific subnet?

Q: Answer-A network administrator has been allocated the block 172.20.0.0/16 and needs to create a subnet that...

To accommodate at least 500 usable hosts, we need 2n 2 500, which requires n 9 host bits 29 2 510, while 28 2 254 is insufficient. A subnet mask with 9 host bits corresponds to 32 9 23, i.e., a 23 mask, which provides exactly enough addresses 510 usable while wasting the fewest addresses compared to a larger block like 22 1022 usable, far more than needed.