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DNS Resolution Process

A team moves its website to a new server at 10:00 in the morning. They update the DNS record, test the site, and everything works.

But for the rest of the day, some customers still reach the old server. Other customers see the new one. Nothing is broken. DNS is doing exactly what it was designed to do.

To understand why, we need to look at how a DNS lookup actually runs. This lesson explains the two ways a DNS server can be asked a question. It also covers the caches that make most lookups fast, and the rules that decide how long an answer is kept.

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Ricardo Franco

Ricardo Franco

· 3 years ago

Negative caching is the process of caching the non-existence of a DNS record. When a resolver receives a query for a non-existent domain or record, it caches this information as a negative response, preventing repeated queries for the same non-existent resource. This reduces the load on DNS servers and improves overall performance.

How a resolver can prevent a query from arriving on it?

I think the resolver uses negative caching to prevent querying DNS servers for non-existent domains. In this case, the text should be "When a resolver receives a response for a non-existent domain". Am I correct?

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Ricardo Franco

Ricardo Franco

· 3 years ago

Who decides when to use recursive or iterative queries?

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