Question : VLSM question

Hi;

I found this link http://fengnet.com/book/CCNA%20Portable/ch02lev1sec2.html#ch02fig01 to explain how VLSM works, it shows step by step to find out each subnet with using VLSM.  This is a good site so far amongs all others site which explain how VLSM works but I still got lost in Step 2.

In Step 2, the ".64"  is picked for Network "A", why it is not ".0"?

The website author used .128/26 to break it into two for network "B", can he use .192/26 to break it instead of .128/26?  If not, why?

Answer : VLSM question

>In Step 2, the ".64"  is picked for Network "A", why it is not ".0"?
He could have used .0/26, but he chose not to and decided to use .0/26 to determine network numbers for serial Links.

>The website author used .128/26 to break it into two for network "B", can he use .192/26 to break it instead of .128/26?  If not, why?
Yes he could have used the .192, it is a matter of preference of which one to use.
I typically leave the last (Few of the last subnets alone for growth)

Billy