Data and Database Administration Questions and Answers

Answer: A

Such a dictionary is a passive data dictionary.

A passive data dictionary is used only by people (designers, users and administrators) as documentation, and is not accessed by the DBMS software, so it must be updated separately from the database.

An active data dictionary is used by the DBMS itself and is updated automatically as the database structure changes. 'Static' and 'dynamic' are not the standard names for this distinction.

Answer: B

The main drawback is that it is vulnerable to privilege propagation.

Under Discretionary Access Control, the owner of an object grants privileges at his own discretion, and with GRANT ... WITH GRANT OPTION the grantee can pass them on, who can pass them on again. The owner soon loses track of who holds access, and a malicious program run by an authorised user can copy data to someone else. DAC has no system-wide rule to stop information flowing this way, which is what Mandatory Access Control adds.

DAC can restrict access at the column level (for example GRANT UPDATE (salary)), privileges are stored persistently in the system catalog, and DAC needs no encryption to work, so the other three options are false.

Answer: D

A data dictionary defines metadata including structure, relationships, constraints, and semantics of data elements across the system.

In system analysis the data dictionary is a central catalogue of data about data: the name, type, size, allowed values, meaning and relationships of every data element, data flow and data store in the system. It keeps the analysts' and designers' definitions consistent.

Holding runtime data instances is the job of the database itself. Transaction consistency and concurrency control belong to the DBMS's transaction manager, and versioned storage of schemas with rollback is a change-management tool.

Answer: D

The answer is Data administration.

Data administration is the managerial function responsible for an organisation's data as a resource: planning and developing its databases and setting and enforcing the standards, policies and controls for how data is defined, used and protected. The technical running of the database software is database administration.

Data resource management is the overall approach of treating data as a business resource, of which data administration is one part. End-user and hypermedia databases are kinds of database, not activities.

Answer: B

The official key gives 'Passwords to prohibit unauthorised access to files' as the answer. Controls such as passwords protect data from being altered or read by people who have no right to the files, which keeps the stored data trustworthy and so is treated here as a data integrity control.

Upper and lower limits on numeric data are validation rules, and the data dictionary options describe a catalogue of definitions and usage, not a control mechanism. The key is kept as printed.

Answer: B

Correct answer: Database design

Where both roles exist, the data administrator owns the conceptual work - data modelling, definitions, metadata, ownership policy - and the database administrator the technical work, beginning with database design: the physical schema, indexes, storage and tuning.

Answer: B

Correct answer: False

Before and after images belong to the database change log. The transaction log records the essential details of each transaction - its identifier, the time, the terminal, the input values - without the images of the records themselves. The two logs serve recovery together, but the statement has attributed the content of one to the other.

Answer: C

Correct answer: Switch to duplicate database

After a system failure the quickest route back to service is to switch to a duplicate - a mirrored or standby database kept in step with the original - so that operations continue while the failed copy is repaired. Rollforward from a backup and log is the fallback where no duplicate exists, and it takes far longer.

Answer: B

Correct answer: False

Concurrency control exists to prevent exactly that interference. Locking or timestamping ensures that concurrent transactions produce the same result as if they had run one after another, so the database is not compromised. Without concurrency control the statement would be true.

Answer: A

Correct answer: True

Restore and rerun reloads the last backup and reprocesses every transaction since, which needs no before-images and is simple to implement. Its weakness is time: the reprocessing takes as long as the original work did, so it is used only where the transaction volume is modest or the failure rare.