What Is a Private IP Address?

Updated on February 26, 2025

Private IP addresses are a key part of modern networking, allowing devices within homes, businesses, and larger organizations to communicate securely and efficiently. They help conserve public IP addresses while keeping internal networks running smoothly.

This article explains private IP addresses, covering their key features, functions, and how they differ from public IPs.

What Is a Private IP Address?

A private IP address is a unique number given to devices in a local network, like at home or in an office. Unlike public IP addresses, private IPs aren’t accessible from the internet. They are only used within internal networks to let devices communicate with each other.

When devices on a private network need internet access, Network Address Translation (NAT) steps in. NAT changes private IP addresses into one public IP address, allowing secure internet access while keeping internal network details hidden.

Private IP Address Ranges 

The private IP address ranges are defined in RFC 1918 (for IPv4) and RFC 4193 (for IPv6). These ranges are reserved specifically for internal network use:

• IPv4 Private IP Ranges:
  • 10.0.0.0 – 10.255.255.255
  • 172.16.0.0 – 172.31.255.255
  • 192.168.0.0 – 192.168.255.255
• IPv6 Unique Local Addresses (ULA):
  • The designated range is fc00::/7, providing private communication for IPv6-enabled devices.

By following these predefined ranges, multiple organizations can utilize private IPs without overlapping, thanks to their non-routable nature.

How Private IP Addresses Work 

Local Communication Within LANs 

Private IP addresses ensure seamless communication between devices within the same LAN without requiring public-facing IPs. Whether it’s connecting printers, accessing shared drives, or interacting with IoT devices, private IP addresses make it possible.

Network Address Translation (NAT) 

NAT is integral to private IP functionality. It allows:

1. Conversion of private IPs to public IPs so devices within a network can access the internet.
2. IP Address Conservation, enabling hundreds of devices to share a single public IP.

Example Use Case: A small business has 50 workstations with IPs in the 192.168.1.x range. Through NAT, all these devices use the same public IP to access the internet, ensuring efficient network operation and security.

Dynamic and Static Assignment with DHCP

• Dynamic Assignment: Private IPs are often automatically assigned to devices within the network via the Dynamic Host Configuration Protocol (DHCP). This ensures efficient IP allocation without manual intervention.
• Static Assignment: For critical infrastructure such as printers, servers, or network switches, private IPs are manually assigned to maintain consistent connectivity.

Key Features and Benefits of Private IP Addresses 

• Non-Routable on the Internet: Private IPs are inherently non-routable, adding a layer of security by preventing unauthorized devices from accessing internal networks directly.
• Unlimited Reuse Across Networks: Since private IPs are restricted to internal use, they can be reused across different organizations and networks without any risk of conflicts.
• Support for Internal Services: Internal services like file sharing, local DNS, and IoT device connectivity rely heavily on private IPs. For example, an office’s NAS (Network Attached Storage) device might use a static private IP for secure file storage and sharing.
• Cost Efficiency: Using private IPs reduces the reliance on expensive public IPs, especially for businesses operating large networks.

Private IP Allocation and Management 

Assigned via Routers Using DHCP 

Most private IP assignments in homes and offices are handled by network routers via DHCP. The router automatically assigns an available private IP to each connected device, simplifying network setup.

Manual Configuration for Specific Roles 

Devices requiring consistent connectivity—such as printers or enterprise servers—are often assigned static private IPs, ensuring reliability.

Subnetting for Efficient Network Traffic 

Subnetting divides private IP ranges into smaller, logical segments. For enterprises managing large networks, this improves organization, optimizes traffic, and enhances security.

Example: A corporate network might divide 192.168.0.0/16 into smaller subnets like 192.168.1.0/24 for HR and 192.168.2.0/24 for IT.

Security Considerations 

While private IPs offer inherent security, IT administrators must leverage additional measures to safeguard internal networks:

• Internal Use Only: Private IPs are isolated from external access, significantly reducing the attack surface for potential cyber threats.
• Firewall and NAT Protections: Firewalls combined with NAT effectively filter and manage traffic, preventing unauthorized access to private networks.
• VPNs for Secure Remote Access: Virtual Private Networks (VPNs) enable secure access to private networks over the internet, a critical feature for remote employees.

Key Terms Appendix 

• Private IP Address: An IP address reserved for internal network communication, not accessible from the internet. 
• Network Address Translation (NAT): A process that translates private IPs to public IPs for external connectivity. 
• Dynamic Host Configuration Protocol (DHCP): A network protocol that dynamically assigns IP addresses to devices within a network. 
• Unique Local Address (ULA): An IPv6 equivalent of private IPs, designated for local communications. 
• Subnetting: The practice of dividing a network into smaller segments for improved efficiency. 
• Virtual Private Network (VPN): A secure tunnel that allows remote access to private networks over the internet. 
• RFC 1918: The standard defining private IPv4 address ranges.