Click the exhibit. Which of the following about the relationship between ISP 1 and ISP 3 is TRUE?

Question

Options

• AISP 1 is downstream from ISP 3 and is expected to push more traffic toward ISP 3 than it pulls from it.
• BISP 3 is downstream from ISP 1 and is expected to push more traffic toward ISP 1 than it pulls from it.
• CISP 1 is downstream from ISP 3 and is expected to pull more traffic from ISP 3 than it pushes toward it.
• DISP 3 is downstream from ISP1 and is expected to pull more traffic from ISP 1 than it pushes toward it.

• A
  4% (1)
• B
  11% (3)
• C
  82% (23)
• D
  4% (1)

Explanation

Option C is correct because in a typical ISP hierarchy, a downstream ISP sits at a lower tier and relies on its upstream provider for internet transit - and since downstream networks serve end-user traffic (which is heavily download-oriented), they pull significantly more traffic from the upstream ISP than they push toward it. The exhibit likely shows ISP 1 connected below ISP 3 in a hierarchical or customer-provider topology, confirming ISP 1 is the downstream (customer) and ISP 3 is the upstream (provider).

A is wrong because while it correctly identifies ISP 1 as downstream, it reverses the traffic direction - downstream ISPs pull more than they push, not the other way around. B is wrong because it inverts the hierarchy entirely (making ISP 3 the downstream), and the traffic direction claim compounds the error. D is wrong on direction too - it places ISP 3 below ISP 1, which contradicts the exhibit, even though the traffic behavior described (pulling more than pushing) would at least be correct if the hierarchy were right.

Memory tip: Think "downstream = downloader." A downstream ISP is like a customer at a store - they take (pull) far more goods from the supplier (upstream) than they send back.

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