Transaction tagging is a technique by which transactions are marked with unique identifiers or headers and traced through the system using agents or sensors at each processing point1. Transaction tagging allows for continuous monitoring and analysis of transaction processing in a high-volume, real-time system by providing visibility into the performance, availability, and reliability of each transaction and its components1. Transaction tagging can also help to identify and isolate errors, bottlenecks, anomalies, and security issues in the system1.

Secure code reviews as part of a continuous deployment program are preventive controls. Preventive controls are controls that aim to prevent or avoid undesirable events or outcomes from occurring, such as errors, defects, or incidents. Secure code reviews are activities that examine and evaluate the source code of a software or application to identify and eliminate any vulnerabilities, flaws, or weaknesses that may compromise its security, functionality, or performance. Secure code reviews as part of a continuous deployment program can help prevent or avoid security issues or incidents from occurring by ensuring that the code is secure and compliant before it is deployed to production. The other options are not correct types of controls for secure code reviews as part of a continuous deployment program, as they have different meanings and functions. Detective controls are controls that aim to detect or discover undesirable events or outcomes that have occurred, such as errors, defects, or incidents. Logical controls are controls that use software or hardware mechanisms to regulate or restrict access to IT resources, such as data, systems, or networks.
Corrective controls are controls that aim to correct or rectify undesirable events or outcomes that have occurred, such as errors, defects, or incidents. References: CISA Review Manual (Digital Version), Chapter 3, Section 3.2

A disaster recovery plan (DRP) is a set of procedures and resources that enable an organization to restore its critical operations, data, and applications in the event of a disaster1. A DRP should be aligned with the organization's business continuity plan (BCP), which defines the strategies and objectives for maintaining business functions during and after a disaster1.
To ensure that a DRP is effective, it should be tested regularly and thoroughly to identify and resolve any issues or gaps that might hinder its execution2345. Testing a DRP can help evaluate its feasibility, validity, reliability, and compatibility with the organization's environment and needs4. Testing can also help prepare the staff, stakeholders, and vendors involved in the DRP for their roles and responsibilities during a disaster3.
There are different methods and levels of testing a DRP, depending on the scope, complexity, and objectives of the test4. Some of the common testing methods are:
* Walkthrough testing: This is a step-by-step review of the DRP by the disaster recovery team and relevant stakeholders. It aims to verify the completeness and accuracy of the plan, as well as to clarify any doubts or questions among the participants45.
* Simulation testing: This is a mock exercise of the DRP in a simulated disaster scenario. It aims to assess the readiness and effectiveness of the plan, as well as to identify any challenges or weaknesses that might arise during a real disaster45.
* Checklist testing: This is a verification of the availability and functionality of the resources and equipment required for the DRP. It aims to ensure that the backup systems, data, and documentation are accessible and up-to-date45.
* Full interruption testing: This is the most realistic and rigorous method of testing a DRP. It involves shutting down the primary site and activating the backup site for a certain period of time. It aims to measure the actual impact and performance of the DRP under real conditions45.
* Parallel testing: This is a less disruptive method of testing a DRP. It involves running the backup site in parallel with the primary site without affecting the normal operations. It aims to compare and validate the results and outputs of both sites45.
Among these methods, full interruption testing would best demonstrate that an effective DRP is in place, as it provides the most accurate and comprehensive evaluation of the plan's capabilities and limitations4. Full interruption testing can reveal any hidden or unforeseen issues or risks that might affect the recovery process, such as data loss, system failure, compatibility problems, or human errors4. Full interruption testing can also verify that the backup site can support the critical operations and services of the organization without compromising its quality or security4.
However, full interruption testing also has some drawbacks, such as being costly, time-consuming, risky, and disruptive to the normal operations4. Therefore, it should be planned carefully and conducted periodically with proper coordination and communication among all parties involved4.
The other options are not as effective as full interruption testing in demonstrating that an effective DRP is in place. Frequent testing of backups is only one aspect of checklist testing, which does not cover other components or scenarios of the DRP4. Annual walk-through testing is only a theoretical review of the DRP, which does not test its practical implementation or outcomes4. Periodic risk assessment is only a preparatory step for developing or updating the DRP, which does not test its functionality or performance4.
References: 2: Best Practices For Disaster Recovery Testing | Snyk 3: Disaster Recovery Plan (DR) Testing
- Methods and Must-haves - US Signal 4: Disaster Recovery Testing: What You Need to Know - Enterprise Storage Forum 5: Disaster Recovery Testing Best Practices - MSP360 1: How to Test a Disaster Recovery Plan - Abacus