IP is the most commonly used communication protocol suite in Internet. Most of us know that this 32bit IP address range has been divided on public and private addresses – what we have at home (private) and what is reachable on Internet (public). But underneath there are more IP pools and not everyone knows that in the IP world there are special address ranges used to cover extra tasks and services provided for us like stream video, routing updates and time updates.
During the exhaustion 32bit ver4 IP pool have changed and the modern division approved by Cisco and Internet Organisations (IEEE and IANA) is the current standard shown below.
Special Addresses of IP version 4
The private address blocks are:
- 10.0.0.0 to 10.255.255.255 (10.0.0.0 /8)
- 172.16.0.0 to 172.31.255.255 (172.16.0.0 /12)
- 192.168.0.0 to 192.168.255.255 (192.168.0.0 /16)
Private space address blocks, as shown in the figure, are set aside for use in private networks. The use of these addresses need not be unique among outside networks. Hosts that do not require access to the Internet at large may make unrestricted use of private addresses. Many hosts in different networks may use the same private space addresses. Packets using these addresses as the source or destination should not appear on the public Internet. The router or firewall device at the perimeter of these private networks must block or translate these addresses.
They are all other addresses from Class A, B and C that do not have special purpose to be used.
Multicast Addresses – reserved for special purposes is the IPv4 multicast address range 126.96.36.199 to 188.8.131.52.
The IPv4 default route as 0.0.0.0. The use of this address also reserves all addresses in the 0.0.0.0 – 0.255.255.255 (0.0.0.0 /8) address block.
One reserved address is the IPv4 loopback address 127.0.0.1 – addresses 127.0.0.0 to 127.255.255.255 are reserved for loopback where hosts direct traffic to themselves.
Link-Local Link Addresses:
IPv4 addresses in the address block 169.254.0.0 to 169.254.255.255 (169.254.0.0 /16) are designated as link-local addresses. These addresses can be automatically assigned to the local host by the operating system in environments where no IP configuration is available. These might be used in a small peer-to-peer network or for a host that could not automatically obtain an address from a Dynamic Host Configuration Protocol (DHCP) server.
The address block 192.0.2.0 to 192.0.2.255 (192.0.2.0 /24) is set aside for teaching and learning purposes. These addresses can be used in documentation and network examples. Unlike the experimental addresses, network devices will accept these addresses in their configurations.