3.21 Disabling Caching

3.21.1 Problem

You want to disable caching on a name server.

3.21.2 Solution

Use the recursion options substatement:

options {
    directory "/var/named";
    recursion no;
};

3.21.3 Discussion

Disabling recursion is one of the most effective ways to limit the amount of memory a name server uses. Processing a recursive query often requires a name server to query another name server, and the name server then caches the response. It's caching that causes a name server's memory usage to increase over time; without caching, a name server tends to use the same amount of memory. If a name server treats all queries as nonrecursive, it won't query other name servers and hence won't cache.

Unfortunately, you can't disable recursion on just any old name server. Many name servers serve one or more authorized resolvers, and those resolvers need their recursive queries answered, well, recursively. Name servers used as forwarders must process recursive queries, too. If you want to limit memory utilization on a name server that needs to process recursive queries, see Section 3.22.

3.21.4 See Also

Section 3.22, for information on limiting how much memory a name server uses, and "A Nonrecursive Name Server" in Chapter 10 of DNS and BIND.