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 ool-ad02da8e.dyn.optonline.net is not the root of its zone.
Instead, try zone transfer on dyn.optonline.net .
Instead, try zone transfer on dyn.optonline.net .