The default DFP availability metric value for the port
of the server. This value is used if the DFP reported
availability value is found to have timed out, has not
been reported yet, or if the associated port for the
virtual hostname has not been configured such that the
correct availability can not be determined from the DFP
information. If the default availability has been
configured for both the port and the server, the port
specific value will be used.