How do stratum levels relate to the distance from a time source?

Question

Exhibit

Options

• AStratum 1 devices are connected directly to an authoritative time source.
• BStratum 15 devices are connected directly to an authoritative time source
• CStratum 0 devices are connected directly to an authoritative time source.
• DStratum 15 devices are an authoritative time source.

• A
  90% (28)
• C
  6% (2)
• D
  3% (1)

Explanation

NTP Stratum Levels Explained

Option A is correct because in the Network Time Protocol (NTP) hierarchy, Stratum 1 servers are directly connected to an authoritative time source (such as a GPS receiver, atomic clock, or radio clock), making them the most accurate network time servers available.

Why the distractors are wrong:

• Option B is incorrect because Stratum 15 devices are near the bottom of the hierarchy, far removed from the time source, and considered unreliable or nearly unusable
• Option C is incorrect because Stratum 0 represents the actual hardware reference clocks (atomic clocks, GPS devices) themselves - they are not networked devices but rather the physical time sources that Stratum 1 servers connect to
• Option D is incorrect because Stratum 15 is the furthest usable stratum level from the source, not an authoritative time source itself

Memory Tip: Think of strata like floors in a building - Stratum 0 is the foundation (the clock itself), Stratum 1 is the ground floor (directly touching the foundation), and each higher stratum number moves you farther away from accuracy. The lower the number, the closer to the source!

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