Data and Database Administration Questions and Answers

Q: Mirrored databases are almost always provided in high-availability systems.

Correct answer: TrueA high-availability system cannot afford the time a restore from backup would take, so it keeps a complete second copy written in step with the first. If one fails the other carries the service immediately. Mirroring guards against media and site failure; it does not guard against a logical error, which is faithfully mirrored too.

Q: Backward recovery is used to reverse the changes made by transactions that have aborted, or terminated abnormally.

Correct answer: TrueBackward recovery, or rollback, applies the before-images in reverse order to undo the effects of a transaction that did not complete. It restores the database to the state it held before the transaction began, which is what makes atomicity possible - a transaction either happens entirely or not at all.

Q: The transaction log includes which of the following?

Correct answer: The essential data of the recordA transaction log records the essential data of each transaction: its identifier, the time, the type of action, and the data affected. The before and after images of changed records are held in the database change log, which is what a rollback or rollforward actually replays.

Q: A traditional data administrator performs which of the following roles?

Correct answer: Resolve data ownership issuesThe distinction is between data administration and database administration. The data administrator is concerned with data as an organisational asset: policy, standards, definitions and who owns which data. Tuning, backup procedures and database security are the technical work of the database administrator.

Q: Which of the following is part of an administrative policy to secure a database?

Correct answer: All of the above.Administrative security is broader than passwords. It covers authentication policies, physical access to the rooms where the systems are, and the terms of external agreements - including how quickly a supplier must respond. A database is only as secure as the weakest of these.

Q: A disaster recovery plan does not need to include the shipment of database backups to other sites.

Correct answer: FalseBackups held only on the site they protect are destroyed with it, so offsite storage is precisely what makes a disaster recovery plan a disaster recovery plan rather than a failure recovery plan. Shipping copies to another location, physically or electronically, is a core requirement.

Q: Which of the following could cause data to be unavailable?

Correct answer: All of the above.Data may be unavailable for any of the three reasons: it may be lost or inaccurate, the server may be down, or the database may be off-line for planned maintenance. Availability is a matter of the whole system, not of the data alone, which is why maintenance windows are themselves an availability cost.

Q: Locking may cause which of the following problems?

Correct answer: DeadlockLocking prevents interference but creates the possibility of deadlock - each transaction waiting for a lock another holds, in a circle. The system must therefore detect deadlocks and break them by rolling a transaction back, which is the price paid for the safety locking gives.

Q: The greatest threat to business security is often internal rather than external.

Correct answer: TrueInsiders already have access, already know where the valuable data is, and are not stopped by the perimeter defences aimed at outsiders. The threat need not be malicious either - carelessness by an authorised user does a great deal of the damage - which is why access control, separation of duties and audit trails matter as much as the firewall.

21.

Mirrored databases are almost always provided in high-availability systems.

A.True
B.False

Answer: A

Correct answer: True

A high-availability system cannot afford the time a restore from backup would take, so it keeps a complete second copy written in step with the first. If one fails the other carries the service immediately. Mirroring guards against media and site failure; it does not guard against a logical error, which is faithfully mirrored too.

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22.

Backward recovery is used to reverse the changes made by transactions that have aborted, or terminated abnormally.

A.True
B.False

Answer: A

Correct answer: True

Backward recovery, or rollback, applies the before-images in reverse order to undo the effects of a transaction that did not complete. It restores the database to the state it held before the transaction began, which is what makes atomicity possible - a transaction either happens entirely or not at all.

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23.

The transaction log includes which of the following?

A.The before-image of a record
B.The after-image of a record
C.The before and after-image of a record
D.The essential data of the record

Answer: D

Correct answer: The essential data of the record

A transaction log records the essential data of each transaction: its identifier, the time, the type of action, and the data affected. The before and after images of changed records are held in the database change log, which is what a rollback or rollforward actually replays.

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24.

A traditional data administrator performs which of the following roles?

A.Tune database performance
B.Establish backup and recovery procedures
C.Resolve data ownership issues
D.Protect the security of the database.

Answer: C

Correct answer: Resolve data ownership issues

The distinction is between data administration and database administration. The data administrator is concerned with data as an organisational asset: policy, standards, definitions and who owns which data. Tuning, backup procedures and database security are the technical work of the database administrator.

Discuss in Forum

25.

Which of the following is part of an administrative policy to secure a database?

A.Authentication policies
B.Limiting particular areas within a building to only authorized people
C.Ensure appropriate responses rates are in external maintenance agreements
D.All of the above.

Answer: D

Correct answer: All of the above.

Administrative security is broader than passwords. It covers authentication policies, physical access to the rooms where the systems are, and the terms of external agreements - including how quickly a supplier must respond. A database is only as secure as the weakest of these.

Discuss in Forum

26.

A disaster recovery plan does not need to include the shipment of database backups to other sites.

A.True
B.False

Answer: B

Correct answer: False

Backups held only on the site they protect are destroyed with it, so offsite storage is precisely what makes a disaster recovery plan a disaster recovery plan rather than a failure recovery plan. Shipping copies to another location, physically or electronically, is a core requirement.

Discuss in Forum

27.

Which of the following could cause data to be unavailable?

A.Data becoming lost or inaccurate
B.The database server
C.Planned database maintenance activities
D.All of the above.

Answer: D

Correct answer: All of the above.

Data may be unavailable for any of the three reasons: it may be lost or inaccurate, the server may be down, or the database may be off-line for planned maintenance. Availability is a matter of the whole system, not of the data alone, which is why maintenance windows are themselves an availability cost.

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28.

Locking may cause which of the following problems?

A.Erroneous updates
B.Deadlock
C.Versioning
D.All of the above.

Answer: B

Correct answer: Deadlock

Locking prevents interference but creates the possibility of deadlock - each transaction waiting for a lock another holds, in a circle. The system must therefore detect deadlocks and break them by rolling a transaction back, which is the price paid for the safety locking gives.

Discuss in Forum

29.

The greatest threat to business security is often internal rather than external.

A.True
B.False

Answer: B

Correct answer: True

Insiders already have access, already know where the valuable data is, and are not stopped by the perimeter defences aimed at outsiders. The threat need not be malicious either - carelessness by an authorised user does a great deal of the damage - which is why access control, separation of duties and audit trails matter as much as the firewall.

Discuss in Forum

30.

Performance analysis and tuning is which of the following?

A.Undertaken one time at the time of a DBMS installation
B.Undertaken one time at the time of the implementation of a new application
C.Undertaken as an ongoing part of the backup of a database
D.Undertaken as an ongoing part of managing a database

Answer: D

Correct answer: Undertaken as an ongoing part of managing a database

Performance tuning is continuous, not a one-off at installation. Data volumes grow, the mix of queries changes, indexes that once helped become a burden on updates - so a database that was well tuned last year may not be now. Monitoring and adjustment are part of ordinary administration.

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