Vlsm

[faisal79]

Hello friends

im new to the forum and this is my first question, im preparing the ccna exam and bought the Todd Lammle's book which im reading now im on chapter three on Subnetting and VLSM, to practice this further i have creating senario and desgined a network, have done vlsm on it, i wanted if anyone kindly could check my answers if im correct, its too big to attach so i will paste my work
i have four routers connected three conected to LAN and one connected to the three routers


172.10.0.0


Net A has 4 hosts
Net B has 3 hosts
Net C has 2 hosts

I need to use vlsm to solve this design problem

This is what I have done

I borrowed 13 bits and left 3 for the hosts, so my subnet is 255.255.255.248

2^13=

2^3-2=6

256-248= 8

My subnets are


0 8 16 24 32 40 ---------------and so on


Net A for Subnet 0/29
Net B for Subnet 8/29
Net C for Subnet 16/29

Im left with subnets 24 32 40---------
I need to do VLSM for the serial links as not to waste IP address

Because I have borrowed 13 and left with 3 this is how my subnet mask looks

11111111.11111111.1111111.11111.000/29

I need to host for the serial links and I have 3 of them

I take subnet 24/29

And borrow one more in the subnet mask 11111111.11111111.11111111.11111100/30

2^1=2 subnets

2^2-2=2 hosts

256-252=4 therefore 24/30
+ 4
--------------
28/30
We have two subnets
Which are 24/30 and 28/30
Which I can apply to the two of the serial link

Im left with one serial link
Applying same process
I will take the other subnet

32/29

And re subnet

Borrowing one yields the result of

2^1=2
2^2-2 =2

256-252=4

32/30
+4
36/30
thanks in advance