if ( tf.getConfig().isDfsDisabled() )
            return null;
        String dom = domain.toLowerCase(Locale.ROOT);
        synchronized ( this.dcLock ) {
            CacheEntry<DfsReferralDataInternal> ce = this.dcCache.get(dom);
            if ( ce != null && System.currentTimeMillis() > ce.expiration ) {
                ce = null;
            }