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Domain Name System (DNS)

DNS maps human-readable names to records (A, AAAA, MX, CNAME, TXT, NS). Resolution is hierarchical: recursive resolvers query authoritative servers from the root (.) downward. Caching TTL reduces load — stale records are a common outage cause after migrations.

Recursive resolution (concept)
Resolver
🌳Root .
📦TLD .com
📚Auth NS
💻Stub client
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