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DNS Load Balancing: Round Robin, Geo & Health

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DNS as a load balancing layer

Before a browser makes any TCP connection, it queries DNS. This makes DNS a powerful traffic distribution point — direct users to the nearest region, split traffic for canary deployments, or automatically failover when a server goes unhealthy.

DNS load balancing operates at a coarser granularity than TCP-level load balancers — it's session-sticky per DNS cache TTL, not per-request. Understanding this limitation explains when DNS LB is appropriate and when a proper load balancer is needed.

Packets in motion — click to inspect:

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