how many ipv4 addresses are there

When the IPv4 address was invented, it was not expected that the Internet would become so popular that millions of devices would use these IP addresses. The IETF defined IPv4 addresses in RFC 791, published in 1981. The first design of IPv4 did not anticipate the Internet’s growth, which created many issues that proved that IPv4 needed to be changed.

Through the years, IPv4 has been updated to address new challenges. However, there are still some significant issues, such as a shortage of IPv4 addresses, end-to-end Connectivity, QoS, etc., which we have listed below. In 2025, the limitations of IPv4 address shortage will have intensified with the proliferation of IoT devices and 5G networks, pushing organizations to accelerate IPv6 adoption to meet global connectivity demands.

Shortage of IPv4 Addresses

The IPv4 addresses have a 32-bit address space. The 32-bit address space is divided into A, B, C, D, and E classes. These classes have a limited number of unique public IP addresses, about 4.3 billion. While there is an increasing number of new IP-enabled devices, always-on connections, and the potential growth of less-developed regions have increased the need for more addresses, causing a shortage of IPv4 addresses.

As the exhaustion and Limitations of IPv4 addresses are recognized, engineers have thought of some solutions, which are not permanent but like a workaround to temporary or short-term solutions, such as CIDR, NAT, and private addressing.  We will discuss these solutions in detail in future articles. As of 2025, solutions like Carrier-Grade NAT (CGN) and IPv4 address reclamation efforts provide temporary relief, but they increase operational costs and complexity in regions like Asia and Africa with rapid internet growth.

Security Related Issues

Internet Protocol Security (IPsec) is a protocol suite that enables network security. Internet Protocol Security (IPsec) provides security for IP version 4 packets, but it is not built-in. In 2025, the lack of built-in security in IPv4 is a growing concern, with cyberattacks leveraging NAT vulnerabilities, prompting the integration of IPsec with zero-trust architectures in enterprise networks.

Address configuration-related issues

Networks and the Internet expand daily, and many new computers and devices use IP. Configuring IP addresses should be simple. We can configure IP version 4 addresses either manually or automatically using DHCP. Nowadays, as almost all devices are IP-enabled, we should have more straightforward means to configure rather than having these devices configured automatically without relying on any administration.

Internet routing table expansion

A routing table selects the best path for sending data. As the number of servers connected to the Internet increases, the number of routes also increases. These IP version 4 routes use memory and processor resources on Internet routers.

Lack of end-to-end connectivity

NAT is generally used within the IPv4 network. NAT allows multiple devices to share a single public IPv4 address. This is difficult for technologies that need end-to-end connectivity because the public IP version 4 address is shared, and the IP version 4 addresses of an internal network host remain hidden.

Impact on Emerging Technologies

In 2025, the lack of end-to-end connectivity hinders peer-to-peer applications like blockchain and real-time gaming, where direct device communication is essential, driving demand for IPv6’s native support.

Quality of service (QoS)

IP version 4 addresses provide Quality of Service (QoS). It relies on the 8-bit TOS field and the identification of the payload. The IP version 4 Type of Service (TOS) field has limited functionality and payload identification.

Header Complexity:

Variable-Length Headers: Optional fields increase processing overhead; IPv6 simplifies headers for efficiency.

IoT and Future Tech Compatibility:

Scalability Issues: Inadequate for IoT’s exponential growth, where IPv6’s 128-bit addressing (3.4×10³⁸ addresses) excels.

Transition Strategies for 2025

Organizations in 2025 are adopting dual-stack (IPv4/IPv6) configurations, tunneling (e.g., 6to4, Teredo), and public IPv4 address markets to ease the transition. Governments are also incentivizing IPv6 deployment to support smart city initiatives.

Conclusion – Limitations of IPv4

IPv6 resolves these limitations of IPv4 with a larger address space, simplified headers, built-in security, and enhanced mobility/QoS features. While IPv4 persists due to legacy systems, transitioning to IPv6 is critical for supporting future internet growth and innovation.