|  | 8.5 | Planning Structured Cabling: Horizontal and Backbone Cabling
| 8.5.5 | Backbone cabling media

TIA/EIA-568-A specifies four types of networking media that can be used for backbone cabling. These include:

- 100 Ω UTP (four-pair)
- 150 Ω STP-A (two-pair)
- 62.5/125 µm multimode optical fiber
- single-mode optical fiber

Although TIA/EIA-568-A recognizes 50 Ω coaxial cable, generally, it is not recommended for new installations. It is anticipated that it will be removed as a choice the next time the standard is revised. Most installations today use the 62.5/125 µm fiber-optic cable, as a matter of course, for backbone cabling.

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