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 203.116.255-4.unknown.starhub.net.sg is not the root of its zone.
Instead, try zone transfer on starhub.net.sg .
Instead, try zone transfer on starhub.net.sg .