Cisco Certified Network Associate (CCNA) Practice Exam

What is the most common version of the Message Digest hash function?

1. MD1

2. MD4

3. MD5

4. MD6

The correct answer is: MD5

The most common version of the Message Digest hash function is MD5. This hashing algorithm, developed by Ronald Rivest in 1991, is widely used across various applications for verifying data integrity and creating digital signatures. MD5 produces a 128-bit hash value, and despite its known vulnerabilities to collision attacks, it remains prevalent due to its efficient performance and ease of implementation in many systems. Other versions of the Message Digest hash function, such as MD1, MD4, and MD6, either did not gain the same level of adoption or were superseded by MD5 in many practical applications. MD4, for example, was an earlier version with known weaknesses that led to MD5 being preferred. MD6 is a newer proposal that has yet to see widespread use, making MD5 the most recognized and commonly utilized version in practice.