DNS Queries

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To resolve a host name or FQDN to an IP address, the client must obtain the appropriate record from a DNS server.

• E.g.,
  • user might type an FQDN into the address bar of a web browser client application
  • client app, referred to as a “stub resolver,” checks its local cache for the mapping
  • If no mapping is found, it forwards the query to its local DNS server
• IP addresses of one or more DNS servers that can act as resolvers are usually set in the TCP/IP configuration
• client communicates with a DNS server over port 53

Resolution process: