Specify cache expiry for com.sun.jndi.dns.DnsContextFactory?

Struggling to find comprehensive documentation for JNDI and DNS. There is some here but it's rather limited.

Specific question: Is it possible to control the caching behaviour of lookups against DNS using com.sun.jndi开发者_如何学编程.dns.DnsContextFactory, for example to say 'do not cache'.

Example code:

Hashtable<String, String> env = new Hashtable<String, String>();
env.put("java.naming.factory.initial", "com.sun.jndi.dns.DnsContextFactory");
env.put("java.naming.provider.url", "dns://mydns/mycompany.com");
....
DirContext ictx = new InitialDirContext(env);

Additionally, is there some comprehensive API documentation that I haven't yet found?