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Chapter 3: The Domain Name System
Finding a Domain
As mentioned earlier, besides providing the daemon to write the DNS entries into the
distributed directory, BIND provides the mechanism for reading the directory. When
your computer needs to find the address for a web site, it queries the DNS servers
you specify (which are usually located on your local network or at your ISP).
Let’s say your browser wants to find www.google.com. BIND’s “client” executes a
command that essentially asks its DNS server whether it knows the address of the
web site. If the DNS server doesn’t know the address, it asks a root server for the
address.
The root server replies, “I don’t know, but I do know where you can find the answer.
Start with the TLD servers for .com.” And it provides the IP address of a server that
knows all the domains (quite a lot!) that are registered directly under .com.
On behalf of your browser, the resolver on the DNS server then queries a .com
server for the address. The .com server says, “I don’t have that information, but I
know a nameserver that does. It has an address of 64.233.167.99 and its name is
ns1.google.com.”
Your friendly DNS server proceeds to the address, reads the directory information
ns1.google.com provides, and comes back to tell your browser the address of www.
google.com. The DNS server then places that information in its cache so it won’t have
to run around looking for ...