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 _2635f6d2a6f96596bb35316ad297ab27.cdn-test.obis.co.jp is not the root of its zone.
Instead, try zone transfer on gskhnxswdw.acm-validations.aws .
Instead, try zone transfer on gskhnxswdw.acm-validations.aws .