Class A Network

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Class A Formulas:
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IP Address:xxx.yyy.zzz.vvv
where the First Octet Range xxx's is:  1 - 126.
and the other's Octet Range xxx or yyy or zzz is: 0 - 255

xxx : Network
yyy.zzz.vvv Hosts

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Definitions:
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Mask : One of the elemnts of the following array: 
In decimal: [M] = {128, 192, 224, 240, 248, 252, 254, 255}
In binary: [M] = {10000000, 11000000, 11100000, 11110000, 11111000, 11111100, 11111110, 1111111}

Subnet Bits = the number of 1 in binary's representation of the Mask

Subnet Mask: 255.m.0.0 and 255.255.m.0  and 255.255.255.m (m belongs to [M])

Max Subnet = 2Subnet Bits

Number of Hosts = (256 - Mask) x 256 x 256 - 2
- 2 stands for that we reseve the first and the last host addresses: The first is called
Subnet ID, the second Broadcast Address

Subnet ID = xxx.0.0.0

Broadcast Address: xxx.(255 - Mask).(255 - Mask).(255 - Mask)

Wildcard Mask: 
0.0.(255 - Mask).255

Host Address Range:
xxx.0.0.1 - xxx.(255 - Mask).(255 - Mask).(255 - Mask)	

	

Calss A:
--------
We mask as follow:

	  Subnet Mask	
			
0	  255.0.0.0	
1         255.128.0.0	
2         255.192.0.0 
3         255.224.0.0 
4         255.240.0.0 
5         255.248.0.0 
6         255.252.0.0
7         255.254.0.0 

8         255.255.0.0 	  
9         255.255.128.0   
10        255.255.192.0 
11        255.255.224.0  
12        255.255.240.0  
13        255.255.248.0 
14        255.255.252.0 
15        255.255.254.0 

16        255.255.255.0   
17        255.255.255.128 
18        255.255.255.192 
19        255.255.255.224 
20        255.255.255.240  
21        255.255.255.248 
22        255.255.255.252  
23	  255.255.255.255 



We vary xxx and fix yyy.zzz to 0.0 (from 0 - 7)
We vary yyy and fix xxx and zzz to 255 and 000 (from 8 - 15)
We vary zzz and fix xxx.yyy to 255.255 (from 16 - 23)


(From 0 to 7)
--------------
Wildcard Mask: 0.(255 - Mask).255.255
Broadcast Address: 12.(255 - Mask).255.255
Hosts: (256 - Mask) x 256 x 256 - 2 
Host Address Range: 12.0.0.1 - 12.(255 - Mask).255.254

(From 8 to 15)
--------------
Wildcard Mask: 0.255.(255 - Mask).255
Broadcast Address: 12.255.(255 - Mask).255
Hosts: (256 - Mask) x 256 - 2 
Host Address Range: 12.0.0.1 - 12.255.(255 - Mask).254

(From 16 to 23)
--------------
Wildcard Mask: 0.255.255.(255 - Mask)
Broadcast Address: 12.255.255.(255 - Mask)
Hosts: (256 - Mask) - 2 
Host Address Range: 12.0.0.1 - 12.255.255.(255 - Mask)


Table:
-------

	  Subnet Mask			Subnet	Max
				Bits 	Subnet		Hosts 
0	  255.0.0.0	    	0 	1	 	256 x 256 x 256 - 2 = 16,777,214
1         255.128.0.0	    	1 	2	 	128 x 256 x 256 - 2 = 8,388,606
2         255.192.0.0 	    	2 	4	 	64 x 256 x 256 - 2 = 4,194,302
3         255.224.0.0  	    	3 	8	 	32 x 256 x 256 - 2 = 2,097,150
4         255.240.0.0  	    	4 	16	 	16 x 256 x 256 - 2 = 1,048,574
5         255.248.0.0  	    	5 	32	 	8 x 256 x 256 - 2 = 524,286 
6         255.252.0.0       	6 	64	 	4 x 256 x 256 - 2 = 262,142
7         255.254.0.0       	7 	128		2 x 256 x 256 - 2 = 131,070

8         255.255.0.0 	    	8 	256		256 x 256 - 2 = 65,534
9         255.255.128.0     	9 	512		128 x 256 - 2 = 32,766
10        255.255.192.0     	10 	1024		64 x 256 - 2 = 16,382
11        255.255.224.0     	11 	2048		32 x 256 - 2 = 8,190
12        255.255.240.0     	12 	4096	 	16 x 256 - 2 = 4,094
13        255.255.248.0     	13 	8192		8 x 256 - 2 = 2,046
14        255.255.252.0     	14 	16384		4 x 256 - 2 = 1,022
15        255.255.254.0     	15	32768		2 x 256 - 2 = 510

16        255.255.255.0       	16 	65536		256 - 2 = 254
17        255.255.255.128     	17 	131072		128 - 2 = 126
18        255.255.255.192     	18 	262144		64 - 2 = 62
19        255.255.255.224     	19 	524288		32 - 2 = 30
20        255.255.255.240     	20 	1048576		16 - 2 = 14
21        255.255.255.248     	21 	2097152		8 - 2 = 6
22        255.255.255.252     	22 	4194304		4 - 2 = 2
23	  255.255.255.255     	23 	8388608		2 - 2 = 0


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Subnet ID Example: 12.0.0.0  
----------------------------


(From 0 to 7)
--------------
Wildcard Mask: 0.(255 - Mask).255.255	
Broadcast Address: 12.(255 - Mask).255.255	
Host Address Range: 12.0.0.1 - 12.(255 - Mask).255.255

Broadcast Address: 12.255.255.255
0 + 255 = 255
Wildcard Mask: 0.255.255.255
12.0.0.1 - 12.255.255.254

Broadcast Address: 12.127.255.255
128 + 127 = 255
Wildcard Mask: 0.127.255.255
Host Address Range 12.0.0.1 - 12.127.255.254


Broadcast Address: 12.63.255.255
192 + 63 = 255
Wildcard Mask: 0.63.255.255
Host Address Range: 12.0.0.1 - 12.63.255.254


Broadcast Address: 12.31.255.255
224 + 31 = 255
Wildcard Mask: 0.63.255.255
Host Address Range12.0.0.1 - 12.31.255.254

Broadcast Address: 12.15.255.255
240 + 15 = 255
Wildcard Mask: 0.63.255.255
Host Address Range12.0.0.1 - 12.15.255.254

Broadcast Address: 12.7.255.255
248 + 7 = 255
Wildcard Mask: 0.7.255.255
Host Address Range12.0.0.1 - 12.7.255.254

Broadcast Address: 12.3.255.255
252 + 3 = 255
Wildcard Mask: 0.3.255.255
Host Address Range12.0.0.1 - 12.3.255.254

Broadcast Address: 12.1.255.255
254 + 1 = 255
Wildcard Mask: 0.1.255.255
Host Address Range12.0.0.1 - 12.1.255.254



(From 8 to 15)
--------------
Wildcard Mask: 0.0.(255 - Mask).255
Broadcast Address: 12.0.(255 - Mask).255
Host Address Range: 12.0.0.1 - 12.0.(255 - Mask).255

Mask : 0 
Wildcard Mask: 0.0.255.255
Broadcast Address: 12.0.255.255
Host Address Range: 12.0.0.1 - 12.0.255.254

Mask : 128 
Wildcard Mask: 0.0.127.255
Broadcast Address: 12.0.127.255
Host Address Range: 12.0.0.1 - 12.0.127.254


Mask : 192
Wildcard Mask: 0.0.63.255
Broadcast Address: 12.0.63.255
Host Address Range: 12.0.0.1 - 12.0.63.254


Mask : 224 
Wildcard Mask: 0.0.31.255
Broadcast Address: 12.0.31.255
Host Address Range: 12.0.0.1 - 12.0.31.254


Mask : 240
Wildcard Mask: 0.0.15.255
Broadcast Address: 12.0.15.255
Host Address Range: 12.0.0.1 - 12.0.15.254

Mask : 248
Wildcard Mask: 0.0.7.255
Broadcast Address: 12.0.7.255
Host Address Range: 12.0.0.1 - 12.0.7.254

Mask : 252
Wildcard Mask: 0.0.3.255
Broadcast Address: 12.0.3.255
Host Address Range: 12.0.0.1 - 12.0.3.2554

Mask : 254
Wildcard Mask: 0.0.1.255
Broadcast Address: 12.255.1.255
Host Address Range: 12.0.0.1 - 12.255.1.254

Mask : 255
Wildcard Mask: 0.0.0.255
Broadcast Address: 12.255.0.255
Host Address Range: 12.0.0.1 - 12.255.0.254




(From 16 to 23)
--------------
Wildcard Mask: 0.0.0.(255 - Mask)
Broadcast Address: 12.0.0.(255 - Mask)
Host Address Range: 12.0.0.1 - 12.0.0.(255 - Mask)

Mask: 0
Wildcard Mask: 0.0.0.255
Broadcast Address: 12.0.0.255
Host Address Range: 12.0.0.1 - 12.0.0.254

Mask: 128
Wildcard Mask: 0.0.0.127
Broadcast Address: 12.0.0.127
Host Address Range: 12.0.0.1 - 12.0.0.126

Mask: 192
Wildcard Mask: 0.0.0.63
Broadcast Address: 12.0.0.63
Host Address Range: 12.0.0.1 - 12.0.0.62

Mask: 224
Wildcard Mask: 0.0.0.31
Broadcast Address: 12.0.0.31
Host Address Range: 12.0.0.1 - 12.0.0.30

Mask: 240
Wildcard Mask: 0.0.0.15
Broadcast Address: 12.0.0.15
Host Address Range: 12.0.0.1 - 12.0.0.14

Mask: 248
Wildcard Mask: 0.0.0.7
Broadcast Address: 12.0.0.7
Host Address Range: 12.0.0.1 - 12.0.0.6

Mask: 252
Wildcard Mask: 0.0.0.3
Broadcast Address: 12.0.0.3
Host Address Range: 12.0.0.1 - 12.0.0.2

Mask: 254
Wildcard Mask: 0.0.0.1
Broadcast Address: 12.0.0.1
Host Address Range: 12.0.0.1 - 12.0.0.0