Why IPv4 Isn’t Exhausted Yet: A Deep Dive into Global IP Allocation

In 2019 many reports claimed that IPv4 addresses were already depleted and that IPv6 would soon replace them, yet two years later IPv4 remains the dominant protocol while IPv6 is only partially deployed.

What is an IP address?

An IP address consists of four decimal numbers separated by dots, each representing an 8‑bit binary octet (0‑255). In total an IPv4 address is a 32‑bit number, giving roughly 4.3 billion possible addresses (0.0.0.0 – 255.255.255.255).

What are public and private IP addresses?

Public addresses are allocated by Internet‑assigned numbers authorities and can reach the global Internet. Private addresses (e.g., 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) are reserved for use inside local networks.

How are IP addresses allocated worldwide?

The allocation hierarchy is:

IANA receives the entire IPv4 pool.

IANA distributes large blocks to the five Regional Internet Registries (RIRs): AFRINIC, APNIC, ARIN, LACNIC, RIPE NCC.

RIRs allocate to Local Internet Registries (LIRs) or National Internet Registries (NIRs).

LIR/NIRs assign to Internet Service Providers (ISPs), which finally allocate to end‑users.

As of 4 Feb 2022, IANA still shows 16 /8 blocks (≈2.68 billion addresses) marked “reserved for future use”, indicating that the IPv4 pool is not completely exhausted.

What is the status of the RIRs?

ARIN (North America) and RIPE NCC (Europe) have exhausted their available IPv4 space, while APNIC, LACNIC, and AFRINIC still have small pools left for allocation.

How does IPv6 compare?

IPv6 uses 128 bits, providing an astronomically larger address space—enough to assign a unique address to every grain of sand on Earth.

How many IPv4 addresses does China have?

China belongs to the APNIC region. Using the APNIC delegated file (

http://ftp.apnic.net/apnic/stats/apnic/delegated-apnic-latest

) and filtering for type “IPv4” and country code “CN”, the analysis finds 8 631 prefixes containing a total of 344 110 080 addresses, about 8 % of the global IPv4 space.

Similar calculations give:

Hong Kong (HK): 2 589 prefixes, 12 573 440 addresses

Macau (MO): 36 prefixes, 336 640 addresses

Taiwan (TW): 872 prefixes, 35 694 848 addresses

Combined, these regions hold roughly 392 705 008 IPv4 addresses (≈9 % of the world total).

How are these Chinese addresses distributed?

The China Network Information Center (CNNIC), acting as an NIR under APNIC, receives allocations from APNIC and further distributes them domestically. CNNIC’s 2023 report shows about 392 million IPv4 addresses in China.

Data from the Taobao IP database ( https://ip.taobao.com/accurancy) indicates that the three major Chinese ISPs control about 74 % of the country’s IPv4 space, and together with the former provider “TieTong” they account for roughly 82 %.

What are the reserved IPv4 address ranges?

0.0.0.0/32 – broadcast to the local host

10.0.0.0/8 – private network

100.64.0.0/10 – carrier‑grade NAT

127.0.0.0/8 – loopback

169.254.0.0/16 – link‑local

172.16.0.0/12 – private network

192.168.0.0/16 – private network

255.255.255.255/32 – limited broadcast

Why hasn’t IPv6 fully replaced IPv4?

Network Address Translation (NAT) lets many private devices share a limited number of public IPv4 addresses.

IPv4 and IPv6 are incompatible; transition requires dual‑stack, tunneling, or NAT64, each with drawbacks.

Reclaiming and re‑allocating unused IPv4 blocks, plus the large share of reserved addresses, slows depletion.

Upgrading to IPv6 demands extensive network redesign, and ISPs lack clear profit incentives.

IPv4 addresses have become expensive, while IPv6 offers no immediate revenue, discouraging investment.

Nevertheless, the finite nature of IPv4 means that IPv6 adoption is essential for meeting future address demand.