Diagnosi metodica

A methodical diagnosis

Work from the client toward the source of the data. First confirm the exact name and record type. Then compare the client’s configured resolver with another trusted resolver, inspect the authoritative answer, and check delegation and DNSSEC where relevant.

Keep the observations separate: a stale cache, a bad recursive resolver, a broken parent-to-child delegation, and an incorrect authoritative record can look similar to an application. Note the queried server, timestamp, TTL, RCODE, and flags. Change one variable at a time and verify the fix from more than one vantage point.

Check your understanding

Choose the best answer. This quiz runs locally and sends no DNS queries to real domains.

Quiz#dns.m4.l4.e1

How can you distinguish an authoritative answer from a cached answer?

উত্তরের বিকল্প

Query only the browserCompare the authority with a recursive resolverChange the record repeatedly

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