I already know how to subnet Class C addresses. Class B subnetting isn't proving to be very difficult, except for one little thing. I'm confused about how to space out the address blocks in the third octet when dealing with networks below /24. Here's an example that I'm having trouble with: Given the IP address 220.127.116.11/19 provide: Network Number: First Usable Host: Last Usable Host: Broadcast: The reason this confuses me is that the third and fourth octets are already mostly made of 1's (binary), therefore doesn't that mean not many addresses are available right off the rip? Also, if anyone has some easy-to-memorize tricks to subnet Class B and A addresses that I can do with paper and pencil I would greatly appreciate the help!