Network+ Training Course Index: Professor Messer’s Course Notes: Discount exam vouchers: - - - - - The IPv4 subnet mask determines which devices are on your local IP subnet. In this video, you’ll learn about the structure of the IPv4 subnet mask and how to calculate the subnet mask based on binary and CIDR-block notations. - - - - - Subscribe to get the latest videos: Calendar of live events: Frequently Asked Questions: FOLLOW PROFESSOR MESSER: Professor Messer website: Twitter: Facebook: Instagram: LinkedIn: