Section: Information System Operations, Maintenance and Support
Explanation:
The sum of RTO and WRT is defined as the Maximum Tolerable Downtime (MTD) which defines the total
amount of time that a business process can be disrupted without causing any unacceptable consequences.
This value should be defined by the business management team or someone like CTO, CIO or IT
manager.
For your exam you should know below information about RPO, RTO, WRT and MTD:
Stage 1: Business as usual
Business as usual

At this stage all systems are running production and working correctly.
Stage 2: Disaster occurs
Disaster Occurs

On a given point in time, disaster occurs and systems needs to be recovered. At this point the Recovery
Point Objective (RPO) determines the maximum acceptable amount of data loss measured in time. For
example, the maximum tolerable data loss is 15 minutes.
Stage 3: Recovery
Recovery

At this stage the system are recovered and back online but not ready for production yet. The Recovery
Time Objective (RTO) determines the maximum tolerable amount of time needed to bring all critical
systems back online. This covers, for example, restore data from back-up or fix of a failure. In most cases
this part is carried out by system administrator, network administrator, storage administrator etc.
Stage 4: Resume Production
Resume Production

At this stage all systems are recovered, integrity of the system or data is verified and all critical systems can
resume normal operations. The Work Recovery Time (WRT) determines the maximum tolerable amount of
time that is needed to verify the system and/or data integrity. This could be, for example, checking the
databases and logs, making sure the applications or services are running and are available. In most cases
those tasks are performed by application administrator, database administrator etc. When all systems
affected by the disaster are verified and/or recovered, the environment is ready to resume the production
again.
MTD

The sum of RTO and WRT is defined as the Maximum Tolerable Downtime (MTD) which defines the total
amount of time that a business process can be disrupted without causing any unacceptable consequences.
This value should be defined by the business management team or someone like CTO, CIO or IT
manager.
The following answers are incorrect:
RPO - Recovery Point Objective (RPO) determines the maximum acceptable amount of data loss
measured in time. For example, the maximum tolerable data loss is 15 minutes.
RTO - The Recovery Time Objective (RTO) determines the maximum tolerable amount of time needed to
bring all critical systems back online. This covers, for example, restore data from back-up or fix of a failure.
In most cases this part is carried out by system administrator, network administrator, storage administrator
etc.
WRT - The Work Recovery Time (WRT) determines the maximum tolerable amount of time that is needed
to verify the system and/or data integrity. This could be, for example, checking the databases and logs,
making sure the applications or services are running and are available. In most cases those tasks are
performed by application administrator, database administrator etc. When all systems affected by the
disaster are verified and/or recovered, the environment is ready to resume the production again.
References:
CISA review manual 2014 page number 284
http://defaultreasoning.com/2013/12/10/rpo-rto-wrt-mtdwth/

Explanation/Reference:
Explanation:
The recovery point objective (RPO) defines the point in time to which data must be restored after a disaster so as to resume processing transactions. Backups should be performed in a way that the latest backup is no older than this maximum time frame. If service levels are not met, the usual consequences are penalty payments, not cessation of business. Organizations will try to set service level objectives (SLOs) so as to meet established targets. The resulting time for the service level agreement (SLA) will usually be longer than the RPO. The recovery time objective (RTO) defines the time period after the disaster in which normal business functionality needs to be restored. The maximum acceptable outage (MAO) is the maximum amount of system downtime that is tolerable. It can be used as a synonym for RTO. However, the RTO denotes an objective/target, while the MAO constitutes a vital necessity for an organization's survival.

Stress testing is one of the most useful software testing procedures since it helps the team to assure the product's performance. Furthermore, it verifies the software's security, dependability, and error-handling capabilities, further enhancing its quality.