Note:  This is a very simplified example of how DNS (Domain Naming System) works.  I'm ignoring things like secondary DNS servers, DNS caching, etc.

Note:  Computers only use the numeric addresses of computers (IP address), not the alphanumeric names.  The alphanumeric names (i.e. www.Unixhub.com) are for humans not computers.
 

  1. Sue wants to go to www.UnixHub.com.  She types "www.Unixhub.com" into her browser.  Her computer ask her ISP's DNS server if it knows the address of www.Unixhub.com (the IP address).  Her ISP's computer doesn't (it doesn't have the address cached).
  2. Her ISP's DNS server goes to the Internet's "Root Server A" (The master server of the Internet run by NSI) and ask it which DNS server knows everything about the domain Unixhub.com (the "authoritative" DNS server for that domain).
  3. Root Server A tells Sue's ISP's DNS server that the DNS server at 216.181.73.179 knows everything about the domain Unixhub.com.
  4. Sue's ISP's DNS server goes to 216.181.73.179 and ask it what is the address (IP) for www.Unixhub.com.
  5. 216.181.73.179 (Unixhub.com's authoritative DNS server) tells Sue's ISP's DNS server that the address (IP) for www.Unixhub.com is 216.181.73.180.
  6. Sue's ISP's DNS server tells Sue's computer that www.Unixhub.com's address is 216.181.73.180 and her computer makes the connection.


Extended Notes:

Copyright © 1993-2001 by Robert Barnes

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