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 xe-4-1-2.a02.frnkge07.de.bb.gin.ntt.net is not the root of its zone.
Instead, try zone transfer on bb.gin.ntt.net .
Instead, try zone transfer on bb.gin.ntt.net .