##### Number of subnets need to consider ??

How many subnets can be implemented if we borrow 4 bits from the next octet of IP address ??

I read it somewhere that in modern scenarios we can also use first and last subnets .So what we need to consider whether all or (all-2) subnets can be implemented?

They will mention this clearly in GATE paper ..

Simple trick... Give first priority to the option 2^n. If no option, go for 2^-2. If it numerical, put 2^n as your answer.

I will tell you why..

If subnet bits=4 then the bits can be populated any where in that particular octet. They need not be consecutive.

If they are consecutive then only we think about 0000,1111(the -2 that u are taliking about). But by default go for 2^n only