DNS

The Domain Name System maps names to IP addresses through a hierarchy of servers, with answers cached for their TTL. Because of caching, DNS changes and DNS-based failover take effect only as caches expire.

Where it shows up in real systems

  • DNS

    Managed DNS answers in about a millisecond thanks to resolver caches. Latency-based, geolocation and failover policies send users to the closest or healthiest region; a low TTL makes failover faster but increases queries.

    In production: Amazon Route 53, Cloudflare DNS, Azure DNS, Google Cloud DNS

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