Chapter 14 – Analyzing IPv4 Networks

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This section reviews the concepts of classful IP networks (A,B,C) 

Chapter examines how to begin with a single IP address and then determine the following facts: 

  • Class  
  • default mask 
  • number of network bits 
  • number of host bits 
  • number of host addresses in the network 
  • network ID 
  • network broadcast address 
  • first and last usable address in the network 
Table 14- Class 128-191 c 192-223 224-239 240-255 2 IPv4 Address Classes Based on First Octet Values First Octet Values 1-126 Purpose Unicast (large networks) Unicast (medium-sized networks) Unicast (small networks) Multicast Reserved (formerly experimental)

IPv4 network classes and related facts: 

  • IPv4 defines five address classes 
  • three of classes (ABC) consist of unicast IP addresses.  
  • unicast addresses identify a single host or interface so that the address uniquely identifies the device in private network 
  • Class D addresses serve as multicast addresses, so that one packet sent to class D multicast IPv4 address can actually be delivered to multiple hosts 
  • Class E were intended for experimentation, but were changed to simply be reserved for future use.  
  • Class can be identified based on the value of the first octet of the address: 
Table 14-3 Key Facts for Classes A, B, and C First octet range Valid network numbers Total networks Hosts per network Octets (bits) in network part Octets (bits) in host part Default mask Class A 1 - 126 I.o.o.o - 126.0.0.0 27-2= 126 224-2 3 (24) 255.0.0.0 Class B 128 - 191 128.0.0.0 - 191.255.0.0 214 = 16,384 216-2 2 (16) 2 (16) 255.255.0.0 Class C 192 - 223 192.0.0.0 - 223.255.255.0 221 = 2,097,152 3 (24) 255.255.255.0

0.0.0.0 are reserved and 127.0.0.0 also 

First, Class B network numbers range from 128.0.0.0 to 191.255.0.0, for a total of 214 networks.  

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