Configuring a Caching Name Server


It's entirely possible to run a name server that is not authoritative for any zones. This is what's known as a caching name server, and its job consists solely of making DNS queries when prompted by clients and storing the results for later use. This is the opposite effect of the forward only option we discussed earlier in this chapter. Whereas a forward only name server would pass off all requests to its forwarder to handle, a caching name server performs all requests that are asked of it by itself and caches the results. Other name servers can use this server as a forwarder, leveraging the work that it has already done.

To configure a caching name server, simply omit any zone statements from your named.conf file other than the ones necessary for its own operation. Listing 32.5 shows such a configuration.

Listing 32.5. A Sample /etc/namedb/named.conf File

/*  * A simple BIND 8 configuration  */ logging {     category lame-servers { null; };     category cname { null; }; }; options {     directory "/etc/namedb"; }; zone "." {     type hint;     file "named.boot"; }; zone "0.0.127.in-addr.arpa" in {     type master;     file "master/localhost.rev"; }; zone "0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.IP6.INT" {         type master;         file "master/localhost.rev"; };

Because a caching name server is simply a "degenerate case" of a fully configured name server, you can easily expand your server's functionality by adding additional zones as time goes on. There is no real fundamental difference between the two "modes."

Your DNS configuration will change with time as your network evolves. Each time a new host is added to your network or changes its name, and each time you take on or remove the name service authority for a zone, you will need to make changes to the configuration. It's a good idea to keep in practice with DNS administration so that these tasks become more natural with time.




FreeBSD 6 Unleashed
FreeBSD 6 Unleashed
ISBN: 0672328755
EAN: 2147483647
Year: 2006
Pages: 355
Authors: Brian Tiemann

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