📝 Traffic conditioners in DiffServ (12 MCQs)

📖 Explanation: An RGB image is built from three independent channels—red, green, and blue. Each channel carries intensity information for its respective primary color, so the image consists of exactly three channels. Therefore the correct answer is the option indicating three channels.

📖 Explanation: Smoothing jitter creates more regular packet spacing, which helps the video decoder maintain a steady buffer. With fewer sudden spikes, the player can pre‑fetch data efficiently, reducing the need for large buffers and thus lowering buffering events. Consequently, viewers experience smoother playback with fewer interruptions.

📖 Explanation: A token‑bucket allows short bursts up to a defined token count before enforcing the average rate, making it tolerant of temporary spikes. In contrast, a leaky‑bucket releases packets at a constant rate, smoothing out bursts and preventing sudden surges. Hence the token‑bucket’s burst‑friendly nature distinguishes it from the leaky‑bucket’s smoothing behavior.

📖 Explanation: 56 levels require $\lceil\log_2 56\rceil = 6$ bits per channel because $2^5=32 < 56 \le 2^6=64$. With three channels (R,G,B), the pixel needs $3 \times 6 = 18$ bits. Therefore the correct answer is the option stating 18 bits per pixel.

📖 Explanation: Traffic conditioners often employ buffers to smooth traffic, which introduces a modest delay (added latency). By queuing packets instead of discarding them, the device reduces the likelihood of loss during congestion. Hence the observed increase in latency accompanied by a decrease in packet loss aligns with the buffering inference.

📖 Explanation: 56 levels need 6 bits per channel; 128 levels need 7 bits. The per‑pixel bit count grows from $3 \times 6 = 18$ to $3 \times 7 = 21$ bits, a $\frac{21}{18}=1.1667$ factor, i.e., about a 16.7 % increase. Thus storage rises by roughly 17 %.

📖 Explanation: Increasing bit depth adds more color precision, enhancing perceived image quality. However, each pixel now carries more bits, so the data volume per frame grows, demanding higher transmission bandwidth to maintain the same frame rate. Therefore higher bit depth simultaneously raises quality and bandwidth requirements.

📖 Explanation: A fixed delay means each packet is held for a predetermined time before transmission. This holding period directly adds to the round‑trip time experienced by the packet, manifesting as additional latency. The delay does not inherently change jitter, throughput, or cause duplication, making added latency the correct cause.

📖 Explanation: Traffic shaping smooths bursts by temporarily storing packets in a buffer and releasing them at the configured rate, thus delaying traffic. Traffic policing, on the other hand, enforces a rate limit by discarding packets that exceed the allowed threshold. Hence the correct pairing is shaping buffers and delays, policing drops excess packets.

📖 Explanation: Pixels per frame = $640 \times 480 = 307{,}200$. Bits per frame = $18 \times 307{,}200 = 5{,}529{,}600$ bits. At 10 fps, bits per second = $5{,}529{,}600 \times 10 = 55{,}296{,}000$. Dividing by 8 yields $6{,}912{,}000$ bytes/s ≈ 6.6 MB/s. Therefore the correct answer is 6.6 MB/s.

📖 Explanation: Allowing unlimited bursts lets large groups of packets arrive simultaneously, overwhelming downstream buffers and links. This sudden surge can cause queue overflows, leading to packet drops. While latency may also increase, the most direct symptom of congestion under such a misconfiguration is an elevated packet‑loss rate.

📖 Explanation: Moving from 6 bits to 8 bits per channel raises the per‑pixel bit count from $3 \times 6 = 18$ bits to $3 \times 8 = 24$ bits, a factor of $24/18 = 4/3$. Consequently, the total data volume grows by about one‑third, meaning the collection’s size would increase roughly 33 % over the original 100 MB.