Private addresses are used for internal network of the company, organisation, or the household. Since they are used for internal network, private addresses can not be used for accessing the Internet. Public addresses, however, can and should be used by organisations for external connection to the Internet. The ranges of available internal IPs are shown in Table 1.
Table 1. IPs reserved for private addresses.
Start IP
End IP
10.0.0.0
10.255.255.255
172.16.0.0
172.31.255.255
192.168.0.0
192.168.255.255
Even if two different companies use the same private addresses for their workstations or networking equipment, the IPs are used privately, so there would be no IP conflict.
If the DHCP server is unavailable to assign routable address, the Private address can be used. For the use, the link-local address has been created. It allows sending and receiving data on a local segment. Basically, that means that everything that is behind router is unreachable. However, two computers connected directly or through the switch can transmit data to each other.
The standard defines available range for the link-local addresses, as shown in Table 2. The range has been defined by the IANA (Internet Assigned Numbers Authority). The standard has been defined for IPv6 too. IPv6 link-local addresses begin with FE80.
