How many backbone levels are allowed in a structured cabling system?

• A. 1 level
• B. 2 levels
• C. 3 levels
• D. 4 levels

Answer: (B)

Backbone cabling is the main vertical pathway that interconnects the building’s telecommunications rooms. Limiting backbone levels to two provides a scalable, maintainable structure for multi‑floor buildings. One level, the building backbone, handles the primary vertical routing between the entrance facility and the main distribution area. The second level, the floor backbone, connects that distribution point to the telecommunications closets on each floor. This two-level approach keeps paths organized, reduces cross‑connect complexity, and supports future upgrades without creating a tangled network. Adding more backbone levels would introduce unnecessary complexity and longer cable routes, while fewer levels wouldn’t adequately support multi-floor interconnections.