Fix processing empty dns result

route/router_dns.go

@@ -82,6 +82,9 @@ func (r *Router) Lookup(ctx context.Context, domain string, strategy dns.DomainS
 		r.dnsLogger.InfoContext(ctx, "lookup succeed for ", domain, ": ", strings.Join(F.MapToString(addrs), " "))
 	} else {
 		r.dnsLogger.ErrorContext(ctx, E.Cause(err, "lookup failed for ", domain))
+		if err == nil {
+			err = dns.RCodeNameError
+		}
 	}
 	return addrs, err
 }