Unlike other systems, Fedora 25 workstation doesn't use stable IPv6 addresses, by default.
For example, with CentOS 7 or Fedora 23, a stable IPv6 is automatically configured (in an IPv6 enabled network where a IPv6 router is present) - i.e. one that is derived from the MAC-address.
That IPv6 address then can be used in an DNS AAAA-record.
In contrast to that, the IPv6 address of a Fedora 25 workstation system doesn't have any relation to its MAC address and doesn't seem to be stable.
How to configure deterministic and stable IPv6 addresses on Fedora 25?