outbound-ip166b.ess.barracuda.com 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 outbound-ip166b.ess.barracuda.com is not the root of its zone.
Instead, try zone transfer on ess.barracuda.com .