To properly protect against unauthorized disclosure of sensitive data, hard disks should be demagnetized before disposal or release.

Explanation/Reference:
Explanation:
The objective of a firewall is to protect a trusted network from an untrusted network; therefore, locations needing firewall implementations would be at the existence of the external connections. All other answers are incomplete or represent internal connections.

To confirm integrity for a hashed message, the receiver should use the same hashing algorithm as the sender' s to create a binary image of the file. A hashing algorithm is a mathematical function that transforms an input data into a fixed-length output value, called a hash or a digest. A hashing algorithm has two main properties:
it is one-way, meaning that it is easy to compute the hash from the input, but hard to recover the input from the hash; and it is collision-resistant, meaning that it is very unlikely to find two different inputs that produce the same hash. These properties make hashing algorithms useful for verifying the integrity of data, as any change in the input data will result in a different hash value. Therefore, to confirm integrity for a hashed message, the receiver should use the same hashing algorithm as the sender's to create a binary image of the file, which is a representation of the file in bits (0s and 1s). The receiver should then compare this binary image with the hash value sent by the sender. If they match, then the message has not been altered in transit.
If they do not match, then the message has been corrupted or tampered with.
References:
Ensuring Data Integrity with Hash Codes
Message Integrity

The IS audit manager should specifically review the detailed evidence of the successes and weaknesses of all contingency testing to substantiate the conclusions of the audit of the corporate disaster recovery test. This is because the detailed evidence can provide the audit manager with a clear and objective picture of how well the disaster recovery plan was executed, what issues or gaps were encountered, and what recommendations or actions were taken to address them. The detailed evidence can also help the audit manager to verify the accuracy, completeness, and validity of the audit findings, as well as to evaluate the adequacy and effectiveness of the disaster recovery controls.
The other options are not as specific or relevant as the detailed evidence of all contingency testing. Overviews of interviews between data center personnel and the auditor may provide some useful information, but they are not sufficient to substantiate the conclusions without supporting evidence from the actual testing. Prior audit reports involving other corporate disaster recovery audits may provide some benchmarking or comparison data, but they are not directly related to the current audit scope and objectives. Summary memos reflecting audit opinions regarding noted weaknesses may provide some high-level insights, but they are not enough to substantiate the conclusions without detailed evidence to back them up.
References:
ISACA, CISA Review Manual, 27th Edition, 2019, p. 2411
Disaster Recovery Audit Work Program2