You are designing a subnet mask for the 172.26.0.0 network. You want 26 subnets with up to 1800 hosts on each subnet. What subnet mask should you use? - Quora
If the range of IP 172.16.0.0/12 is class B , why can I use the subnet mask 255.255.255.0 in this range? - Quora
![The TCP/IP Guide - IP "Supernetting": Classless Inter-Domain Routing (CIDR) Hierarchical Addressing and Notation The TCP/IP Guide - IP "Supernetting": Classless Inter-Domain Routing (CIDR) Hierarchical Addressing and Notation](http://www.tcpipguide.com/free/diagrams/ipcidr.png)