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Q3(b) · DNS cache popularity

2024-02-06 · AI-only Sem V variant

Exact historical variant. Current-syllabus questions solved; excluded topics and source limitations stated.

Q3(b). If you can access departmental local-DNS caches, propose a way to roughly determine which external web servers are most popular among departmental users. Explain limitations. [5 marks]

Answer

Take repeated authorized snapshots of cache entries or resolution counters and group names by web service. A record frequently present or refreshed after expiry suggests repeated resolutions; query logs/counters, if available, provide a better frequency estimate than a single cache snapshot.

Do not equate DNS queries with page views. TTL duration, client/browser caches, shared CDN names, prefetching and multiple domains per page bias the result. A long-TTL unpopular name may remain cached longer than a popular short-TTL name. The result is only a rough popularity indicator, not a count of users or visits.