Implementing Cisco Enterprise Advanced Routing and Services (ENARSI) — Question 46

Which list defines the contents of an MPLS label?

Answer options

• A. 20-bit label; 3-bit traffic class; 1-bit bottom stack; 8-bit TTL
• B. 32-bit label; 3-bit traffic class; 1-bit bottom stack; 8-bit TTL
• C. 20-bit label; 3-bit flow label; 1-bit bottom stack; 8-bit hop limit
• D. 32-bit label; 3-bit flow label; 1-bit bottom stack; 8-bit hop limit

Correct answer: A

Explanation

The correct answer is A, as it accurately details the structure of an MPLS label, which consists of a 20-bit label, a 3-bit traffic class, a 1-bit bottom stack indicator, and an 8-bit TTL. Options B and D incorrectly specify a 32-bit label and use 'flow label' instead of 'traffic class'. Option C also misstates the label size and uses 'hop limit' instead of TTL.