How many bits does DSCP use to provide QoS marking options?

The correct answer is C. 6. DSCP (Differentiated Services Code Point) uses 6 bits in the IP header's DS field, allowing for 2⁶ = 64 possible QoS marking values (0–63), which is why C is correct. The other options are common distractors: 8 bits is the full size of the original ToS (Type of Service) byte…

QoS Fundamentals

Question

Options

How the community answered

(26 responses)

C
92% (24)
D
4% (1)
E
4% (1)

Explanation

DSCP (Differentiated Services Code Point) uses 6 bits in the IP header's DS field, allowing for 2⁶ = 64 possible QoS marking values (0–63), which is why C is correct. The other options are common distractors: 8 bits is the full size of the original ToS (Type of Service) byte that the DS field replaced; 16 bits has no relevance to DSCP and likely appears to confuse it with other header fields; 4 bits relates to the original IP Precedence sub-field within ToS; and 3 bits is exactly the size of IP Precedence itself, the older and simpler QoS marking system that DSCP superseded. A helpful memory tip: think "DSCP = 6" by remembering that DSCP expanded IP Precedence's 3 bits by doubling them (3 × 2 = 6), giving far more granular traffic classification options.

Topics

#DSCP#QoS Marking#DiffServ#IP Header Fields

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