Книга: Linux Network Administrator Guide, Second Edition

Caching-only named Configuration

Caching-only named Configuration

There is a special type of named configuration that we'll talk about before we explain how to build a full name server configuration. It is called a caching-only configuration. It doesn't really serve a domain, but 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 only the first query for a particular host is actually sent to the name servers on the Internet. Any repeated request will be answered directly from the cache in your local name server. This may not seem useful yet, but it will when you are dialing in to the Internet, as described in Chapter 7, Serial Line IP and Chapter 8, The Point-to-Point Protocol.

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 named.local; localhost network
cache  .  named.ca; root servers

In addition to this named.boot file, you must set up the named.ca file with a valid list of root name servers. You could copy and use Example 6.10 for this purpose. No other files are needed for a caching-only server configuration.

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