See, the whole network is structured such that :
- One Laptop is connected to the main router
- Desktop D1 is connected to main router. This desktop has two interfaces and both the interfaces are connected to two different networks - only one interface is connected to THIS network.
- Similarly for desktop D2
- One Wifi router, which creates a subnet within this network. This subnet consists of the Wifi router, two mobiles and one Tablet. So, overall, this subnet will require :
- One IP address for the network main wifi router
- One IP address for directed broadcast
- One IP address for each mobile
- One IP address for Tablet
So, total used IP addresses are :
- One IP address for the main router
- One IP address for Laptop
- One IP address for D1 and One IP address for D2
- Six IP addresses for the wifi subnet (Because even if there are 3 devices connected to the router, we need to allocate addresses in powers of 2)
So, total 10 IP addresses are used. Therefore, 6 IP addresses are still available.
Please correct if I am wrong.