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 be-ag1-2-r2-2.summitgw.net is not the root of its zone.
Instead, try zone transfer on summitgw.net .
Instead, try zone transfer on summitgw.net .