Is this application IPv6 ready?

IPv6 deployment has reached a point where the hardest problems are no longer necessarily in routers and access networks. Increasingly, the question is whether the applications running on those networks have actually been tested without IPv4.

For many years, "IPv6 support" could mean that an application worked on a dual-stack host. But as IPv6-only networks and transition mechanisms such as NAT64 become increasingly common, applications need to remain functional when IPv4 is unavailable. This is particularly important for public digital services: governments may mandate IPv6 support for public-facing services, but network-level IPv6 connectivity does not guarantee that the application itself will work correctly.

This presentation will look at IPv6 application readiness from an operational perspective: what should actually be tested, which failure modes are commonly missed, and how to test applications across IPv4-only, dual-stack, IPv6-only with NAT64, and strict IPv6-only environments.

We will also share our experience developing V6bench at NIC.br, an open-source tool created to help setting up a laboratory to test applications' IPv6 readiness. Rather than presenting it as a product, we will use it as a practical example of how operators, developers and SRE teams can build repeatable IPv6 application-testing environments and invite the community to help evolve the approach.