Non-repudiation is the ability to prove that a message or document was sent or signed by a particular person, and that the person cannot deny sending or signing it. Non-repudiation can be achieved by using cryptographic techniques, such as hashing and digital signatures, that can verify the authenticity and integrity of the message or document. Non-repudiation can be useful for legal, financial, or contractual purposes, as it can provide evidence of the origin and content of the message or document. References = Non-repudiation - CompTIA Security+ SY0-701 - 1.2, CompTIA Security+ SY0-301: 6.1 - Non-repudiation, CompTIA Security+ (SY0-701) Certification Exam Objectives, Domain 1.2, page 2.

Data in transit is data that is moving from one location to another, such as over a network or through the air.
Data in transit is vulnerable to interception, modification, or theft by malicious actors. A VPN (virtual private network) is a technology that protects data in transit by creating a secure tunnel between two endpoints and encrypting the data that passes through it2.

Detailed Explanation:
A software development life cycle (SDLC) policy outlines responsibilities, best practices, and standards for developing, deploying, and maintaining secure systems and software. Reference: CompTIA Security+ SY0-
701 Study Guide, Domain 5: Security Program Management, Section: "Policies and Standards".

A staging environment is a controlled setting that closely mirrors the production environment but uses a subset of customer data. It is used to test major system upgrades, assess their impact, and demonstrate new features before they are rolled out to the live production environment. This ensures that any issues can be identified and addressed in a safe environment before affecting end-users.
References = CompTIA Security+ SY0-701 study materials, particularly in the domain of secure system development and testing environments.