log.debug("Removing expired " + links.map);
            }
            roots.remove(root);
            links = null;
        }

        if (links == null) {
            log.trace("Loadings roots");
            final String refServerName = domain;
            dr = fetchRootReferral(tf, domain, root, refServerName);
            links = cacheRootReferral(tf, domain, root, roots, dr, links);