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 ssvlnv2qzf5h2qknmofumuzyxugfyiruzrqwoblk6jyici77n42a.mx-verification.google.com is not the root of its zone.
Instead, try zone transfer on google.com .
Instead, try zone transfer on google.com .