N10-009 Question 181
Single answerA network administrator is upgrading access-layer switching in a three-story office building. The building has one MDF on the first floor where the ISP demarc, core switch, firewall, and servers are located, and one IDF closet on each upper floor for user cable terminations. The new 48-port switches will be installed in the IDF closets. During planning, the administrator notices the switches are deeper than the old models and use port-side exhaust airflow. Each IDF closet has a 2-post relay rack positioned with the switch ports facing the room door, and there is only 6 inches of clearance between the front of the rack and the wall behind it. Which action is the BEST way to ensure a proper installation?
- A
Install the new switches in the MDF instead of the IDFs so that airflow direction is less important, and patch all upper-floor users back to the MDF
- B
Keep the switches in the IDFs, replace the 2-post relay racks with properly sized 4-post cabinets or racks that support the switch depth, and orient the switches so the port-side exhaust has adequate clearance
- C
Mount the switches sideways in the existing 2-post racks so the exhaust vents upward, eliminating the need to consider front and rear clearance
- D
Leave the existing racks in place and solve the airflow issue by adding more patch panels above the switches to redirect the hot air away from the ports
Show answer and explanation
Correct answer: B
Explanation
The best answer is to keep access-layer switches in the IDFs and correct the physical installation issues. In structured cabling design, the MDF is the central distribution point, while IDFs serve localized areas or floors and connect back to the MDF through backbone cabling. Access switches that connect end users are normally installed in the IDF closest to those users. From an installation perspective, rack size and depth matter: deep switches may not be suitable for older 2-post relay racks without proper support, and many manufacturers recommend 4-post mounting for deeper or heavier equipment. Airflow direction is also critical. With port-side exhaust, the port side expels hot air, so that side must have sufficient clearance and must not be blocked by a wall or other obstruction. These considerations are consistent with common vendor hardware installation guides and with TIA-aligned telecommunications room practices that emphasize proper equipment support, cable management, and thermal planning.
- A. Incorrect.
This is incorrect. Access-layer switches that serve upper-floor users are typically placed in the IDF closets nearest those users, with uplinks back to the MDF. Moving all access switches to the MDF would be impractical because horizontal copper cabling has distance limits, commonly 100 meters for Ethernet over twisted pair. It also ignores the actual installation concerns: rack depth/support and airflow clearance. Airflow direction still matters regardless of whether equipment is in the MDF or IDF.
- B. Correct.
This is correct. IDFs are the appropriate location for floor-level access switches that aggregate user terminations and uplink to the MDF. Because the new switches are deeper than the old models, a properly sized rack or cabinet is needed; 4-post support is commonly preferred for deeper and heavier network devices. In addition, port-side exhaust means the side with the ports is the hot-air exhaust side, so that side must not be blocked. Ensuring adequate clearance and correct orientation aligns with common vendor installation guidance and data/telecom room best practices.
- C. Incorrect.
This is incorrect. Sideways mounting in a rack is not a standard installation method for fixed switches and can create support, cable management, and cooling problems. It also does not guarantee proper airflow because switch cooling is designed for a specific intake/exhaust path. Changing the physical orientation arbitrarily can interfere with the intended thermal design and servicing access.
- D. Incorrect.
This is incorrect. Patch panels do not redirect or manage switch exhaust in a meaningful way. Airflow planning requires maintaining clear intake and exhaust paths and installing equipment in racks that physically support the device correctly. Adding more patch panels could actually worsen congestion and cable density near the exhaust side.