“IP not in subnet range” simply means that you are attempting to use  an IP address that doesn’t belong to the block of IP’s defined by the subnet mask in question. Based on our VLSM example above, if the network address and subnet mask for LAN B is 192.168.4.0 and 255.255.255.192 (/26) respectively, and you are trying to use an ip address of 192.168.2.2 then you will get an “ip not in subnet range” error. The only usable host IP addresses in range are 192.168.4.1–192.168.4.62 as shown on Table 9.0.