Changes since SOA version
IXFR is a zone transfer request that returns changes since a specific SOA version. Enter the SOA version to request changes since then.
Not an apex domain
The domain i5s9kdka6enm0oit3koj3egjdg910g90.builder.nu is not the root of its zone.
Instead, try zone transfer on builder.nu .
Instead, try zone transfer on builder.nu .