Which of the following descriptions about the comparison between URL filtering and DNS filtering are correct? (Multiple choice)

Question

Options

• AURL filtering has less impact on device performance than DNS filtering
• BURL filtering has a smaller control range than DNS filtering
• CURL filtering has finer granularity of control than DNS filtering
• DDNS filtering can perform access control earlier than URL filtering

• A
  31% (16)
• B
  69% (36)

Explanation

URL filtering and DNS filtering operate at different layers of the network stack, which explains why B, C, and D are all correct. DNS filtering blocks at the domain-resolution stage - before any connection is made - so it acts earlier (D) and sweeps entire domains, covering all subdomains and every page underneath (making its control range larger, confirming B). URL filtering kicks in after DNS resolution, during the actual HTTP request, so it can distinguish between individual pages on the same domain (e.g., allow example.com/safe while blocking example.com/restricted), giving it far finer granularity (C).

Why A is wrong: URL filtering requires deep inspection of the full HTTP request (and often SSL decryption), which is computationally heavier than DNS filtering, which only checks a domain name string - so URL filtering has more performance impact, not less.

Memory tip: Think of DNS filtering as a city-gate guard (blocks the whole city early, broad reach) and URL filtering as a room-by-room inspector (arrives later, but can approve or deny each individual room). The inspector is more precise but does more work and comes second.

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