--- old/src/java.naming/share/classes/com/sun/jndi/ldap/LdapCtx.java	2017-01-25 16:14:20.830433462 +0000
+++ new/src/java.naming/share/classes/com/sun/jndi/ldap/LdapCtx.java	2017-01-25 16:14:20.690432525 +0000
@@ -200,6 +200,23 @@
     private static final String REPLY_QUEUE_SIZE =
         "com.sun.jndi.ldap.search.replyQueueSize";
 
+    /*
+     * Name of the DNS provider class used by
+     * {@code LdapCtxFactory.getUsingURL()} to resolve ldap server urls.
+     * {code DefaultLdapDnsProvider} is used by default.
+     *
+     * A DNS provider must implement the {@code BiFunction} interface.
+     * In addition, the provider class must be public and must have a
+     * public constructor that accepts no parameters.
+     *
+     * The {@code BiFunction.apply(String url, Hashtable<?,?> env)} method
+     * takes two parameters:
+     *
+     * {@code String url}: The {@code Context.PROVIDER_URL}
+     * {@code Hashtable<?,?> env}: The LdapCtx environment properties.
+     */
+    static final String DNS_PROVIDER = "com.sun.jndi.ldap.dnsProvider";
+
     // ----------------- Fields that don't change -----------------------
     private static final NameParser parser = new LdapNameParser();