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 81371_fw01_fw02-vip.den03.viawest.net is not the root of its zone.
Instead, try zone transfer on den03.viawest.net .
Instead, try zone transfer on den03.viawest.net .