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DNS Clients DNS Servers .edu DNS Servers on the Internet What Is a DNS Query?
A query is a request for name resolution to a DNS server. There are
two types of queries: recursive and iterative
DNS clients and DNS servers both initiate queries for name
An authoritative DNS server for the namespace of the query
will either: Check the cache, check the zone, and return the requested IP
address Return an authoritative, “No”
A non-authoritative DNS server for the namespace of the
query will either: Forward the unresolvable query to a specific query server
called a Forwarder Use root hints to locate an answer for the query How Recursive Queries Work
A recursive query is a query made to a DNS server, in which the DNS
client asks the DNS server to provide a complete answer to the query DNS server checks the forward lookup
zone and cache for an answer to the query
Recursive query for
Local DNS Server How Root Hint Works
Root hints are DNS resource records stored on a DNS server that list
the IP addresses for the DNS root servers
DNS Servers Cluster of
Root (.) Servers
Root Hints DN...
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- Spring '11