A private IP address is assigned to a device within a closed network and is not readily available to search for on the internet. To facilitate the distribution of IP addresses within networks and organizations, private addresses were created. It is easier to understand a private IP address by explaining an actual scenario.
Let's imagine that you have a home network - You have a desktop computer, a laptop, a smartphone and a tablet. These devices all connect to the internet through a central router. Instead of each device on your network being allocated with a public IP address, the only public IP Address you will use is assigned to the router.
A router will be assigned a public IP address, but will then assign a private address using the DHCP protocol to each device on your network. The devices on your network will communicate with each other using their private IP address, and the router will use its public IP address to facilitate communication over the internet. When connecting to the internet, your private IP addresses will remain hidden, and only the routers public IP address is visible.
Reserved for private networks.
The private address space specified in RFC 1918
is defined by the following three address blocks:
- 192.168.0.0 - 192.168.255.255
- 172.16.0.0 - 172.31.255.255
- 10.0.0.0 - 10.255.255.255
The 192.168.0.0/16 private network can be interpreted either as a block of 256 class C network IDs or as a 16-bit assignable address space (16 host bits) that can be used for any subnetting scheme within the private organization. The 192.168.0.0/16 private network allows the following range of valid IP addresses: 192.168.0.1 to 192.168.255.254.
The 172.16.0.0/12 private network can be interpreted either as a block of 16 class B network IDs or as a 20-bit assignable address space (20 host bits) that can be used for any subnetting scheme within the private organization. The 172.16.0.0/12 private network allows the following range of valid IP addresses: 172.16.0.1 to 172.31.255.254.
The 10.0.0.0/8 private network is a class A network ID that allows the following range of valid IP addresses: 10.0.0.1 to 10.255.255.254. The 10.0.0.0/8 private network has 24 host bits that can be used for any subnetting scheme within the private organization.