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010-151 DCTECH study materials
010-151 DCTECH study resources

010-151 DCTECH: Data Center Hardware and Cabling

010-151 DCTECH · Work through your exam, one topic at a time.

All guide sections

Data Center Hardware and Cabling

This domain checks whether you can identify physical infrastructure, choose the right media and optics, and install equipment so power, airflow, and cabling stay reliable. Questions often pair a distance or speed with a connector type, or ask which power design meets a redundancy requirement.

Racks, power and airflow

  • A rack unit (RU/U) is 1.75 in (44.45 mm); a standard rack is 42U, but usable space shrinks after PDUs and cable managers.
  • Cold aisles face server fronts; most Cisco UCS and Nexus gear moves air front-to-back. Fixed-airflow units cannot be reversed in the field.
  • Redundancy: A/B feeds from separate PDUs on separate circuits; N+1 adds one spare PSU; 2N duplicates the whole path. Two PSUs on one PDU give no feed redundancy.
  • PDU types: basic, metered, monitored, switched. Per-outlet metering lets you track draw before adding load.

Media and optics

  • Cat5e/Cat6/Cat6a copper: 100 m channel limit; Cat6a for 10GBASE-T.
  • Twinax DAC: passive at 1-5 m, active for longer runs; lowest cost and latency inside a rack.
  • Multimode OM3/OM4 at 850 nm: 10GBASE-SR reaches 300 m on OM3 and 400 m on OM4; 40GBASE-SR4 reaches 100 m on OM3 and 150 m on OM4.
  • Single-mode at 1310 nm: 10GBASE-LR reaches 10 km.
  • Connectors: LC duplex for SFP/SFP+, SC on older patch panels, MPO/MTP 12-fiber for 40G/100G parallel optics.
  • Form factors: SFP+ 10G, SFP28 25G, QSFP+ 40G, QSFP28 100G. Match optic to port speed and fiber type.

Worked example

A UCS C240 M6 sits 2 m from a Nexus 93180YC-EX and has a 10G SFP+ port. Choose a passive Twinax DAC: the run is short, so copper costs less and draws less power than SR optics. A second server 90 m away in another row should use OM4 multimode with 10GBASE-SR at both ends; single-mode LR would work but costs more than needed.

Traps

  • Putting a 10GBASE-LR single-mode optic on a multimode patch cord.
  • Using an MPO cable without checking polarity and gender.
  • Assuming a 40G QSFP+ port breaks out to 4x10G without a supported breakout cable.
  • Counting total rack units instead of usable U after PDU space.