 
  
However, this solution is not optimal, because all name lookups will still go through your SLIP/PPP link. If you worry about the bandwidth this consumes, you can also set up a caching-only name server. It doesn't really serve a domain, but only acts as a relay for all DNS queries produced on your host. The advantage of this scheme is that it builds up a cache, so that most queries have to be sent over the serial line only once. A named.boot file for a caching-only server looks like this:
           ; named.boot file for caching-only server
           directory                            /var/named
           primary       0.0.127.in-addr.arpa   db.127.0.0 ; loopback net
           cache         .                      db.cache   ; root servers
In addition to this name.boot file, you also have to set up
the db.cache file with a valid list of root name servers.
This is described toward the end of the Resolver Configuration
chapter.