A2. a) Describe the main recovery techniques that many DBMS (Database Management Systems) provide to safeguard and protect data as a result of EACH of the following events: i) Human Error: an employee may unintentionally delete some data or may have used a routine that has modified the data unknowingly in a way that would cease the DBMS from interacting with the database effectively. ii) Network failure where a connection of a database to a shared network has been interrupted. iii) Database software failure: this might be the result of the DBMS crashing unexpectantly. iv) Media Failure with possible loss of all or some data. v) National catastrophe such as an earthquake or flood meaning the entire operation of the host DBMS is lost. (15 marks) b) Describe the security measures and precautions that a DBA (Database Administrator) must have in place to prevent the database from being subject to hacking, for example, someone trying to steal data. (5 Marks) c) A data dictionary holds information that is crucial for the correct operation of a database. If the data dictionary is lost, the database cannot operate. Describe the contents of a typical data dictionary. (5 marks)