Cap Theorem easy
Is the Domain Name System (DNS) considered CP or AP?
- A CP - It must maintain absolute real-time accuracy to prevent users from being directed to incorrect or malicious servers.
- B Neither; DNS is a decentralized flat-file system that does not utilize standard distributed consensus or CAP-related protocols.
- C AP - Updates propagate slowly through a hierarchy; the system prioritizes almost 100% uptime over immediate global data consistency.
- D Blockchain-based; it uses a cryptographically verified distributed ledger to ensure that all IP address updates are globally atomized.
Answer: C. AP - Updates propagate slowly through a hierarchy; the system prioritizes almost 100% uptime over immediate global data consistency.
DNS is a classic example of an AP system. When you change your server's IP address, it can take hours (due to TTL settings and intermediate caching) to propagate globally. During this time, the system is 'Inconsistent'—some users see the old IP, while others see the new one. However, the system's 'Availability' is almost perfect, as DNS servers are designed to always provide a response.
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