Functional testing contributes to software quality assurance by ensuring that the software functions according to specified requirements, thus improving its reliability and usability.

Test Data Subsetting is a strategy aimed at reducing storage needs by selecting a subset of data relevant to the test scenarios, without compromising quality.

In functional testing, addressing inadequate access controls and permissions is particularly challenging. While other aspects like identifying vulnerabilities or cryptographic algorithm weaknesses are testable at the code level, ensuring proper access controls require a comprehensive understanding of the application's functionality and potential user scenarios, making it a nuanced challenge in the realm of security testing within functional testing processes.

Test execution optimization can be achieved through the implementation of test automation. Automated testing helps in executing a large number of test cases efficiently, providing quicker feedback on code changes. Additionally, integrating testing into the continuous integration process ensures rapid and continuous testing, contributing to overall efficiency in the software development lifecycle.

Exploratory Testing heavily depends on the tester's experience and intuition. Testers use their knowledge to explore the application and identify defects without predefined test scripts or detailed test cases. This method allows flexibility in adapting to changing conditions and discovering unforeseen issues.

The primary purpose of a test case is to enhance communication between teams by providing clear instructions on what to test, how to test, and the expected results.

Scenario-based Testing involves designing test cases based on realistic scenarios that mimic actual usage conditions. In the context of a new network routing algorithm, this technique allows the testing team to evaluate how well the algorithm performs under various conditions, ensuring its correctness and efficiency. It helps in identifying potential issues that may arise in real-world scenarios, making it an effective technique for testing complex algorithms like network routing in a telecom company.

Continuous Deployment (CD) involves automatically releasing changes to production after successful CI processes. This approach enables a seamless and rapid delivery pipeline, reducing manual interventions and accelerating the time from code commit to deployment. It emphasizes automating the deployment process for efficient and reliable releases.

Executing additional test cases is not a part of test closure activities. Test closure involves tasks like documenting lessons learned, finalizing test environments, and releasing the software product. The focus is on summarizing the testing process, not continuing to execute new test cases.

Agile methodology impacts the frequency of functional testing cycles by emphasizing iterative testing. In Agile, development is carried out in short iterations or sprints, making it crucial to conduct testing continuously throughout the development process. This iterative approach ensures that functional testing is an integral part of each cycle, promoting early detection of issues and rapid feedback.