Computer Networks - lecture2Application Layer and DNS

Resource record root com resource record dns clients

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Unformatted text preview: oot “.” .com Resource Record 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 resolution 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 DNS zone and cache for an answer to the query Recursive query for mail1.nwtraders.com 172.16.64.11 Computer1 Database 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 Cluster of DNS Servers Cluster of Root (.) Servers Root Hints DN...
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