UnixReview: The Top 50 Things to Know to Pass the Sair Exam 103

Here are three:

1. There are three classes of IP addresses that can be assigned to
   hosts, identifiable by the first octet:
   • Class A hosts fall within the range of 1-126
   • Class B hosts fall within the range of 128-191
   • Class C hosts are between 192-223
2. The address range from 224.0.0.0 to 239.255.255.255 is known as
   Class D and is used for IP multicasting. Class E addresses are
   between 240-255, with 255 being used for broadcasting.
3. A private address range exists within each of the classes and
   can be used for hosts that do not directly communicate with the
   outside world (other than through an address translator/proxy
   server). The ranges, by class, are:
   • Class A hosts use 10.x.x.x
   • Class B hosts in the private range are between 172.16.x.x to
     172.31.x.x
   • Class C hosts use 192.168.x.x