Network+: ch8 Subnetting, and intro to NAT

Question 1

Each IP class subnet are the same withing each octet, write out the binary and decimal numbers

Answer 1

Binary           Decimal 
00000000          0            
10000000          128          
11000000           192         
11100000            224        
11110000             240       
11111000              248      
11111100               252

Question 2

How many subnets and hosts per subnet can you get from the network 192.168.1.0 255.255.255.224?

Answer 2

Step 1: Determine the classful mask.

192 = Class C
Class C default mask = 255.255.255.0

Step 2: Determine how many additional subnet bits exist beyond the classful boundary.

transform the mask to binary. In the octet that we are working in count the 1s, those are the subnet bits

Step 3: Determine how many host bits remain.

We are still only working in the fourth octet. Since three bits went to the subnet in step 2, we have five host bits (0's) remaining.

Step 4: Find the exponents of both subnet bits and host bits using the cheat sheet:

Subnet Bits = 2^3 = 8
Host Bits = 2^5-2 = 30

Subnets? 2^x, x= number of 1s
Hosts? 2^y-2, y = number of zeros

Question 3

write the the steps to find the last valid IP address.

Answer 3

1. Convert the shorthand subnet mask to decimalFigure out which octet the mask is in, the 8th bit represents the previous octet or /8, /16 or/24 count up towards given mask to find the decimal number./26 = 255.255.255. + Two additional subnet bits.
   (8+8+8) = 24, 26 -24 gives 2 additional subnet bits.
   Go to your cheat sheet, start at the bottom (128) and count up two, starting with 128. You should get to 192.
   Thus, our decimal subnet mask is 255.255.255.192
2. Determine the block size.

    The block size is listed in the block size column parallel to your decimal mask.
    The block size is 64.

3. What is my Network ID (First IP)?Subnet ID??
   every subnet, the first and the last IP addresses are reserved:First IP Address = Network IDLast IP Address = Broadcast Address. The broadcast address is used for a specific type of network traffic that is destined for every device attached to a network.

	Example:
	IP Address = 192.168.1.1
	Subnet Mask = 255.255.255.0
	Network ID = 192.168.1.0
	Broadcast Address = 192.168.1.255
	Usable IP's = 192.168.1.1 - 192.168.1.254

We are simply looking for the largest multiple of the block size without going over the given octet number.

What are the valid subnets? 256 – subnet mask = block size, or increment number.
Start counting at zero in blocks until you reach the subnet mask value, and these are your subnets. If the given address is in the middle of the subnet choose the one below it.

Since we are working in the fourth octet and the block size is 64, the first network is 192.168.1.0.

4. What is the next Network ID?next network subnet ID
   First network ID + block size
   Broadcast address (last IP in the subnet):
   Next subnet ID minus 1
   First Usable IP (the address after the network ID):
   Network ID plus 1
   Last Usable IP (the address before the broadcast address):
   Broadcast address minus 1

Question 4

Write out the 14 line cheat sheet for subnetting

Answer 4

Host Bits | Block Size / Exponents | Decimal Mask Value 
0                              1		    			255
1 				2					254
2 				4					252	
3 	                        8					248
4 				16					240
5 				32					224
6 				64					192
7 				128					128
8 				256	
9 				512	
10				1024
11   			        2048
12				4096