_3400e8e51e6888fe78c22bc613cc31e7.spf.dnssmarthost.net IXFR zone transfer

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 _3400e8e51e6888fe78c22bc613cc31e7.spf.dnssmarthost.net is not the root of its zone.
Instead, try zone transfer on spf.dnssmarthost.net .