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THE CS NOTES

IP Addresses

IP address network classifications are divided into five classes (A, B, C, D, and E) based on their first few bits and value range.

IP Address xxxxxxxx.xxxxxxxx.xxxxxxxx.xxxxxxxx (32 bits)

00000000 = 0 and 11111111 = 255

[ Network id | Host id ]
Below we enclose network bit's inside '()' like (xxxxx)


Each Classess Network Range  in Binary:
A -> 0(0000000).0.0.0 - 0(1111111).255.255.255
B -> 10(000000.0).0.0 - 10(111111.255).255.255
C -> 110(00000.0.0).0 - 110(11111.255.255).255
D -> 1110(0000.0.0.0) - 1110(1111.255.255.255)
E -> 1111(0000.0.0.0) - 1111(1111.255.255.255)




No. of Networks  eachy type:
Network Bits = A=8, B=16, C=24, D=NA, E=NA
A : 2^(8-1) = 2^7 = 128 network
B : 2^(16-2) = 2^14 = 16384 Networks
C : 2^(24-3) = 2^21 = 2097152 Networks
D : 2^(32-4) = 2^28 = 26843546 Networks
E : 2^(32-4) = 2^28 = 26843546 Networks


Total 2^8 = 128  values are possible i.e.  0 to 127


Network Range in Binary to  Decimal
A : 0(0000000) - 0(11111111) <=> 0 - 127 (0+2^7-1 = 0+128-1)
B : 10(000000) - 10(111111) <=> 128 - 191 (128+2^6-1 = 128+64-1)
C : 110(00000) - 110(11111) <=> 192 - 223 (192+2^5-1 = 192+32-1)
D : 1110(0000) - 1110(1111) <=> 224 - 239 (224+2^4-1 = 224+16-1)
E : 1111(0000) - 1111(1111) <=> 240 - 255 (240+2^4-1 = 240+16-1)


Network Range Decimal
A : 0.0.0.0 - 127.255.255.255
B : 128.0.0.0 - 191.255.255.255
C : 192.0.0.0 - 223.255.255.255
D : 224.0.0.0 - 239.255.255.255
E : 240.0.0.0 - 255.255.255.255
ClassFirst BitsStarting IP RangeEnding IP RangeDefault Subnet MaskNo. of Hosts
A0xxxxxxx1.0.0.0127.255.255.255255.0.0.016,777,214
B10xxxxxx128.0.0.0191.255.255.255255.255.0.065,534
C110xxxxx192.0.0.0223.255.255.255255.255.255.0254
D1110xxxx224.0.0.0239.255.255.255N/A (Multicast)N/A
E1111xxxx240.0.0.0255.255.255.255N/A (Reserved)N/A

Key Points:

Section titled “Key Points:”
  • Class A: Used for large networks (Governments, Large Orgs)
  • Class B: Used for medium-sized networks
  • Class C: Used for small networks (Most common for businesses)
  • Class D: Used for Multicasting (No subnetting)
  • Class E: Reserved for Experimental purposes