CDN intelligently resolves the domain name and returns the IP address of the CDN node with the fastest response speed to the local DNS. Which of the following is the correct ordering of the CDN…

Question

Options

• A1245376
• B1243576
• C1243756
• D1234567

• A
  4% (1)
• B
  4% (1)
• C
  84% (21)
• D
  8% (2)

Explanation

Option C (1243756) is correct because CDN resolution doesn't follow a simple linear path - it involves a CNAME redirection mid-chain. After the local DNS queries the authoritative DNS (step 4 before step 3 in some numbering schemes reflecting root → TLD → authoritative hierarchy), the authoritative DNS returns a CNAME pointing to the CDN's scheduling domain rather than a direct IP. Only then does the CDN's intelligent DNS (GSLB) evaluate factors like latency and load to return the optimal node IP back to the local DNS.

Why the distractors fail:

• A (1245376) places the CDN intelligent scheduling response too early, before the proper DNS hierarchy traversal completes - the CDN DNS can't respond until the local DNS reaches it via the CNAME chain.
• B (1243576) misorients the final steps, swapping when the CDN node IP is returned to the local DNS vs. when the user actually reaches the CDN edge node.
• D (1234567) assumes a perfectly sequential flow, ignoring that CNAME redirection causes the local DNS to loop back and query a new target (the CDN DNS) mid-process rather than proceeding straight down a list.

Memory tip: Think of CDN resolution as a "detour" - the DNS lookup starts normally, hits a CNAME sign that redirects it to the CDN's traffic cop (GSLB), and only then does it get directed to the fastest node. The non-linear steps in option C reflect that detour; any answer that looks too sequential (like D) should raise a red flag.

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