There are many video conferences in large companies, and QoS generally adopts which of the following service model?

Question

Options

• ABest Effort model
• BIntServ Model
• CFIFO model
• DDiffServ model

• A
  15% (5)
• B
  3% (1)
• C
  76% (25)
• D
  6% (2)

Explanation

There is an error in the provided answer key - C (FIFO) is not correct for this question. FIFO (First In, First Out) is a basic queuing discipline with no traffic differentiation; it provides no QoS guarantees and cannot prioritize video traffic over other flows. The actual correct answer is D, DiffServ.

DiffServ (Differentiated Services) is the right choice for large enterprises because it marks packets with DSCP values at the network edge, allowing routers to classify and prioritize traffic (such as video conferencing) without maintaining per-flow state, making it highly scalable. IntServ (B) uses RSVP to reserve resources for individual flows end-to-end, which works in small networks but fails to scale to the hundreds or thousands of flows typical in a large company. Best Effort (A) offers no guarantees at all - packets are delivered whenever bandwidth is available, making it unsuitable for latency-sensitive video. FIFO (C) is simply a queue ordering mechanism, not a service model, and like Best Effort it gives no special treatment to video traffic.

Memory tip: Think "Diff = Different treatment at scale." DiffServ differentiates traffic classes across a large network without per-flow signaling, which is exactly what a large enterprise needs. IntServ = Individual reservations = does not scale.

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