DNS Operation
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To establish a connection to a remote host, a user program
sends a query to the resolover, asking the IP number of a specified
hostname;
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The resolver starts with knowledge of at least one
nameserver;
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The resolver processes a user query by asking a known
nameserver for the information (IP for the remote host);
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If the nameserver has the answer, it will give it.
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The local nameservers knows the addresses of other
nameservers;
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If the remote host is in a zone for which the local nameserver
is not authoritative, queries will be sent to other nameservers,
starting with root servers to find out the delegated nameserver for
the top-level-domain, the subdomain and so on;