Cisco Certified Network Associate (CCNA) Practice Exam

What does the Message Digest (MD) hash function produce?

1. A variable-length hash value

2. A 128-bit fixed length hash value

3. A 256-bit hash value

4. A 64-bit hash value

The correct answer is: A 128-bit fixed length hash value

The Message Digest (MD) hash function, specifically referring to the widely known MD5 variant, produces a fixed-length hash value that is 128 bits long. This means that regardless of the size of the input data, the output will always be a 128-bit hash. This characteristic of producing a constant-length output is a fundamental property of cryptographic hash functions. In terms of context, other hash functions like SHA-256 (a member of the SHA-2 family) provide a 256-bit hash value, while SHA-1 offers a 160-bit hash length. Thus, MD5 is specifically recognized for its 128-bit output, making the selection of a 128-bit fixed length hash value the correct choice in this instance.