The State of IPv6 Adoption in 2025: Progress, Pitfalls, and Pathways Forward

They say old habits die hard, and even in the digital landscape, this rings true. Despite years of explosive growth, with more businesses and users online with each passing year, the transition to Internet Protocol version 6 (IPv6) remains slow and steady as the cracks in Internet Protocol version 4 (IPv4) become increasingly evident. However, the transition to IPv6 is not just a technological upgrade; it is essential for the future of connectivity.

What is IPv6, and why is it better?

Simply put, we're running out of space. IPv4 addresses have been exhausted, and spring-cleaning the internet to make space is hardly tenable when there are roughly 1.2 billion websites with 194 million actively maintained.

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IPv6 addresses are significantly larger, 128-bit IP addresses. Unlike IPv4, which is a 32-bit address and has limited address space for unique IPs, IPv6  has a near-infinite IP capacity—up to 340 undecillion addresses. IPv6 also has several built-in improvements for security, efficiency, and performance like IPsec and encryption.

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The Internet Assigned Numbers Authority (IANA) has already allocated the last blocks of IPv4 address space to regional Internet registries, underscoring the urgent need for the broader adoption of IPv6.  

The current state of IPv6 adoption

Larger address spaces, more efficient routing, and extensive networks; on paper IPv6 sounds like a technologist's dream come true. Yet, global adoption has lagged. Data shows that IPv6 traffic to Google, while increasing, is still below 50%. As of early 2025, global IPv6 adoption stands at slightly over 43%, based on IPv6 traffic to Google. Looking at the data by country, the United States is only slightly above 50%, while France, Germany, and India have much higher adoption rates at 80%, 75% and 74% respectively. 

The adoption rate is higher in other countries for numerous reasons. France in particular has benefited from mobile network operators increasing IPv6 subscriptions and support from major Internet Service Providers (ISP). In the United States, ISP hesitancy remains a hurdle for increased adoption.

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The slow, steady trend toward IPv6 adoption would make sense—if it wasn't for the fact that IPv6 is a 30-year-old protocol. 

Key moments in the "Uh-Oh, we're running out of IPs" timeline

Fairly early into the internet—back before viral content and even memes—it became apparent that 4.3 billion IP addresses were, in fact, an insufficient number. In 1994 (yes, IPv6 is arguably vintage), the Internet Engineering Task Force (IETF) started designing IPv6 as a long-term solution to the problem of limited digital space.

Almost immediately, efforts began to extend the life of IPv4, but in 2011, the IANA officially ran out of free IPv4 addresses. By 2020, Europe's regional internet registry had depleted its IPv4 pool, meaning ISPs and businesses had to recycle or buy IPv4 addresses at inflated secondary prices.

Several "life extenders" have delayed the exhaustion of IPv4, creating less urgency around the transition.  Here are the key ones:

• Classless Inter-Domain Routing (CIDR): Replaced the old classful IP system, which wasted huge chunks of IP space and allowed more efficient subnetting.
• Variable Length Subnet Masking (VLSM): Allows networks to use different-sized subnets instead of fixed sizes.
• Network Address Translation (NAT): Allows multiple devices in a private network to share one public IPv4 address, drastically reducing demand.
• Reserved private IP ranges: Reserved private IP ranges (e.g., 192.168.x.x, 10.x.x.x, 172.16.x.x) for internal use, keeping them off the public internet.

Additionally, secondary markets have popped up for organizations to buy and sell IPv4 addresses. In the past, Microsoft purchased IPv4 addresses from the failing dot com business Nortel for $7.5 million. 

IPv4 isn't dead (yet), and other IPv6 pitfalls

While the continuation of IPv4 is a key factor, other circumstances contribute to the slow adoption of IPv6.

Lack of ISP Incentives

Internet Service Providers (ISPs) control large segments of the network and its associated infrastructure, and many have been slow to push IPv6, instead opting to continue using IPv4 by employing NAT to mitigate address shortages. Many ISPs, especially smaller ones, don't yet offer IPv6 services or monitoring. Without robust IPv6 support from ISPs, users might encounter connectivity issues or restricted access to IPv6-enabled websites.

IPv6 is expensive to deploy

While it has become commonplace for endpoints (desktops, laptops, tablets, smartphones) to be replaced with relative frequency, this is less true of routers and switches. Over the last ten years, many companies have released devices that support IPv6 connectivity, however, if a business has not invested in new hardware the transition can have substantial upfront costs. Planning and using existing resources wisely can help manage costs.

Lack of backward compatibility

Leslie Daigle, former Chief Internet Technology Officer for the Internet Society, said, "The lack of real backward compatibility for IPv4 was the single critical failure." As a result, there is no single, standardized way to communicate between IPv4 and IPv6 devices. Organizations can leverage a dual-stack router to accommodate both protocols, which creates additional work for internal teams.

DNS considerations 

Configuring a DNS server in an IPv6 network can be demanding for network administrators. IPv6 addresses are longer and use hexadecimal notation and shorthand notations that can be confusing to administrators more familiar with IPv4, all of which makes manual configuration and troubleshooting more prone to errors. Ensuring compatibility with existing IPv4 infrastructure, managing address resolution, and handling the various IPv6-specific settings require a deep understanding of both network protocols.  

Additionally, DNS servers still prioritize IPv4 because of its widespread use. However, DNS providers are slowly increasing IPv6 compatibility, urging clients to consider the switch.

The potential impact of popular domains

Popular domains can significantly drive IPv6 adoption. When major websites shift to IPv6, it sends a strong message across the internet community. It can encourage smaller sites to follow suit. The more widespread IPv6 becomes, the more networks will prepare to meet its requirements. This change can create a cycle, pushing clients and providers to embrace IPv6. As such, the influence of these domains is powerful in increasing the adoption rate and normalizing IPv6 usage.

IPv6 is still the future (eventually)

IPv6 solves IPv4’s limitations and is essential for the future of the internet. But as long as IPv4 still works (thanks to life-extending technologies like NAT), businesses and ISPs have little urgency to move, and adoption will likely continue at a slow pace. However, government support for the transition has steadily increased over the last several years, and maintaining a dual-stack network is a poor long-term solution for IT and network teams.

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