A common error in the UNIX system occurs during configuration of bind, a directory name server. The time-to-expire field is set at 0.5 because the administrator believes that this field unit is minutes (and wishes to set the time to 30 seconds) However, bind expects the field to be in seconds and reads the value as 0 - meaning that no data is ever expired.

a) Classify this vulnerability using the RISOS model, and justify your answer
b) Classify this vulnerability using the PA model and justify your answer
c) Classify this vulnerability using the Aslam's model and justify your answer