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 2001-1960-0020-6000-0000-0000-0000-0000.f45216b0bf237b38bf82ce18ffcc9927.ip6.frontiernet.net is not the root of its zone.
Instead, try zone transfer on ip6.frontiernet.net .
Instead, try zone transfer on ip6.frontiernet.net .