About Private IP Addresses and their Ranges

What is the Purpose of a Private IP Address?

A private IP address serves important purposes for both home and business networking. Local networks in schools, offices, hotels or airports can function with private IP addresses. A private address not just improves the security of your network, but also conserves addressing space for public addresses.

In computer networking, there are certain ranges of addresses referred to as private IP addresses. Groups that enforce Internet Standards create IP address ranges. When a range is available, Internet Service Providers and their subscribers never fall short of public IPs. Local IP address is another term for a private IP address.

Private IP Addresses

How Do You Identify a Private IP Address?

The Internet Assigned Numbers Authority (IANA) classifies certain IP address ranges as private. Some of these private IP address ranges are:

  • 16 million addresses in the range 10.0.0.0 to 10.255.255.255.
  • 169.254.0.0 to 169.254.255.255 which is a private IP address range for Automatic Private IP Addressing (APIPA).
  • More than 1 million addresses in the range 172.16.0.0 to 172.31.255.255.
  • More than 65,000 addresses in the range 192.168.0.0 to 192.168.255.255.
  • As many as 4 million IP addresses belonging to the 100.64.0.0/10 range are available for use in carrier grade NAT.

How Does an External Device Connect with a Private IP Device?

When a device on a local network is assigned a private IP address, it cannot communicate directly with other Internet devices. Even devices on the Internet cannot connect to a private IP device directly. A Network Address Translation (NAT) restores proper communication.

The purpose of Network Address Translation (NAT) is to mask the private IP address and enable message transfer to devices working with a private IP address. The function of NAT enables a security layer when the communication takes place.

What is the Difference between Private and Reserved IP Addresses?

Reserved IP addresses are not the same as private IP addresses. Reserved IP addresses do not participate in network communication. However, private IP addresses are available for local networks and not assigned as public addresses to Internet-based devices.

What are Some Examples of Private IP Addresses?

Some of the commonly employed private addresses in local networks include the following:

  • 127.0.0.1 is a loopback address for testing network adapters. When a device sends a message to 127.0.0.1, it comes back to the same device. A test result is usually attached to the message. IP applications test network interfaces through the 127.0.0.1 IP address. Theoretically, the Internet Protocol reserves the range 127.0.0.0 to 127.255.255.255 for loopback operations. This range is not part of the Class A range of addresses and is hence never assigned to a public device.
  • Another address range starting from 0.0.0.0 and ending at 0.255.255.255 is also not part of the Class A range of addresses. There is no specific purpose attached to addresses following the format 0.x.x.x. However, when a device attempts to connect to the Internet with an address belonging to this range, it will not be able to send and receive messages effectively.

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