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 host-128-121-237-87.netrange-121.netbuild.net is not the root of its zone.
Instead, try zone transfer on netrange-121.netbuild.net .
Instead, try zone transfer on netrange-121.netbuild.net .