Final answer:
The statement is true; older versions of Windows before Windows XP SP1 do not support IPv6, while it is enabled by default in most modern Windows operating systems.
Step-by-step explanation:
The statement that not all versions of Windows support IPv6, and some that do enable it by default, is true. Initial support for IPv6 was introduced in Windows XP with Service Pack 1 and it's been enabled by default since Windows Vista. However, some older versions prior to Windows XP SP1 do not support IPv6. With the growing number of devices needing internet connections, IPv6 adoption has increased due to its larger address space compared to IPv4. Modern versions of Windows not only support IPv6 but also prefer it over IPv4 when possible. Nevertheless, for compatibility reasons, both IPv4 and IPv6 are typically supported and can run simultaneously on these systems.