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 dsl092-249-248.sfo4.dsl.speakeasy.net is not the root of its zone.
Instead, try zone transfer on sfo4.dsl.speakeasy.net .
Instead, try zone transfer on sfo4.dsl.speakeasy.net .