some doubt in VLSm

[Pramod.purohit]

Hello all,

when working with Variable length subnet mask I noticed on thing that if we assign the larger subent at first and then smaller one on a router's interface (I mean in descending order like 64, 16, 8 and so on) it works fine. But if we assign addresses to the subnets where we require less host addresses and them assign to larger subnet it gives overlapping error.

so does it mean we should start with big subnet first and then go to smaller?
or it is becoz I am doing some wrong while doing VLSM?

one more doubt, can we start next subnet from where we left on such as my first subnet is 64 , second is 4 and now can I start my thirs subnet from 68?

Pleaseeeee help me out.

Thanks for all your support and help.