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What are non-routable IP addresses?

Non-routable IP addresses may seem like a tough nut to crack initially, but we’re here to clarify things. These unique identifiers are central to data transfer within private networks, yet they’re not directly routable over the broader internet. Read on as we unravel the mystery behind non-routable IPs’ purpose and role in maintaining network efficiency.

What are non-routable IP addresses?

Understanding IP Addresses

Internet Protocol address definition

An Internet Protocol address, more commonly referred to simply as an IP address, is a unique numeric address that identifies a single device on a network. A typical IPv4 address contains four numbers separated by dots. Each number is in the 0-255 range. An example of an IP address might look like:

Because an IP address holds much information about yourself, safeguarding it is very important. While your IP address will not expose your personal information, like a phone number or home address, cybercriminals can still use your IP address for malicious purposes. An IP leak may lead to the disclosure of your geographical location, snooping on your online activity, or even a cyberattack on your networks or devices.

What are non-routable IP addresses, and why are they important?

Non-routable IP addresses, also known as private IP addresses, are reserved numbers that computers use to communicate with each other within a private network, like your home or office. Basically, non-routable IPs work like a secret language within the network. They help ensure efficient device communication processes and seamless private network operations and safeguards your online fortress.

With the growth of the internet and devices connected to the web, the demand for public IPs has increased too. Non-routable IPs ensure that devices operating on a private network have reserved IPs.

Another important aspect of private IPs is local network security. Private networks usually contain sensitive information, important documents, and confidential files, which, thanks to non-routable IP addresses, cannot be directly accessed from the outside world. Therefore, it becomes more challenging for cybercriminals to crack into your systems.

Non-routable IP addresses enable local network isolation. Using a private IP address, you can create a guest or dedicated network for your smart devices. This may help you control who accesses your network and separate activities or data.

Non-routable IP address ranges as defined by RFC 1918

RFC 1918 specified a private address space of IPs reserved for internal networks:

  • – (
  • – (
  • – (

This non-routable address space is authorized for internal use only and is not routable on the internet. It allows organizations to control communications within the internal network and safeguard sensitive information. While these private IPs can only be used within the network, companies use network address translation (NAT) to translate non-routable IPs to public IP addresses and successfully access the broad internet.

Network address translation and non-routable IP addresses

NAT is a technique to connect multiple non-routable IPs in a network to a single public IP before communicating with the internet. While every device has its own private, non-routable IP, it still needs a public IP to transfer the information onto the internet. A device sends a request to NAT, which issues a public IP and transmits data to the internet. When the internet responds, NAT sends the information back to the device by reversing the process and ensuring seamless communication.

NAT is a crucial screw in the networking machine, providing your home or office network devices with a single public IP and easing the communication processes with the internet.

Transition from IPv4 to IPv6: The role of non-routable IP addresses

The role of non-routable IP addresses has significantly changed due to the switch from IPv4 to IPv6. IPv4’s constrained address space required NAT and non-routable IPs to preserve public addresses. Every device that uses IPv6 has a unique, routable address and offers an almost infinite number of unique addresses. Non-routable addresses are useful for security since they hide underlying network architecture, adding an extra degree of security.

IPv6 is still being applied, therefore many networks still use IPv4 today, so non-routable IPs and NATs still are very relevant and important to this day.

Routable vs. non-routable IP addresses

Let’s look at the differences between routable and non-routable IPs:

Routable IPsNon-routable IPs
Allows data forwarding from one network to another.Doesn’t allow forwarding of data from one network to another.
Transfers data from one network to another via router.Cannot use routers to transmit data over the network.
Contains a network address and a device address.Only contains a device address.
Used for large networks.Designed for local networks.
Requires technical know-how to maintain.Less complex than routable IPs.
Has direct internet access.Needs NAT for internet access.
Can operate in different networks.Limited to the same network.
Directly exposed to the internet and needs extra security measures.Isolated from the internet, therefore offers an additional layer of security.

How do VPNs use non-routable IP addresses for secure internet communication?

Virtual private networks (VPNs) use non-routable IPs to ensure secure communication between networks and the internet. As soon as you connect to a VPN, your device receives a private IP address within the VPN’s network used to establish a secure communication channel. A VPN never sends your requests straight to the intended website. It routes the data through the VPN server first, which uses its own IP to communicate with the internet on your behalf. Such a process ensures that your actual IP remains a secret and the website doesn’t recognize your identity. Data return follows the same path in reverse.

Premium VPNs like NordVPN secure your online activities, making it more difficult for cybercriminals to target your sensitive information and devices and enhancing your privacy online.

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