diff --git a/server.go b/server.go
index d147ca1..ab64711 100644
--- a/server.go
+++ b/server.go
@@ -39,7 +39,7 @@ func (srv *server) serveUDP() {
 
 	udpconn, err := net.ListenUDP("udp", &net.UDPAddr{IP: _ip, Port: _port})
 	if err != nil {
-		log.Fatalf("listen udp error", err)
+		log.Fatalf("listen udp error %s", err)
 	}
 
 	defer udpconn.Close()
diff --git a/server_https.go b/server_https.go
index 8f14cfa..8a6d001 100644
--- a/server_https.go
+++ b/server_https.go
@@ -52,10 +52,15 @@ func (srv *server) handleHTTP2Req(w http.ResponseWriter, r *http.Request) {
 	}
 	reply := false
 	for _, up := range srv.upstreams {
+		log.Debugf("from %s query upstream %s", r.RemoteAddr, up.String())
+		log.Debugln("query", msg.Question[0].String())
 		m, err := queryUpstream(msg, up)
 		if err == nil {
 			w.Header().Set("content-type", "application/dns-message")
 			w.WriteHeader(http.StatusOK)
+			for _, a := range m.Answer {
+				log.Debugln("result", a.String())
+			}
 			d, _ := m.Pack()
 			w.Write(d)
 			reply = true
diff --git a/server_tcp.go b/server_tcp.go
index 92317a1..dce483b 100644
--- a/server_tcp.go
+++ b/server_tcp.go
@@ -19,8 +19,13 @@ func (srv *server) handleTCP(c net.Conn) {
 		}
 		reply := false
 		for _, up := range srv.upstreams {
+			log.Debugf("from %s query upstream %s", conn.RemoteAddr(), up.String())
+			log.Debugln("query", msg.Question[0].String())
 			m, err := queryUpstream(msg, up)
 			if err == nil {
+				for _, a := range m.Answer {
+					log.Debugln("result", a.String())
+				}
 				log.Debugln("got reply", m.String())
 				conn.WriteMsg(m)
 				reply = true
diff --git a/server_udp.go b/server_udp.go
index 8baa6ec..5c7f909 100644
--- a/server_udp.go
+++ b/server_udp.go
@@ -14,8 +14,13 @@ func (srv *server) handleUDP(buf []byte, addr net.Addr, conn *net.UDPConn) {
 		return
 	}
 	for _, up := range srv.upstreams {
+		log.Debugf("from %s query upstream %s", addr, up.String())
+		log.Debugln("query", msg.Question[0].String())
 		m, err := queryUpstream(msg, up)
 		if err == nil {
+			for _, a := range m.Answer {
+				log.Debugln("result", a.String())
+			}
 			d, _ := m.Pack()
 			conn.WriteTo(d, addr)
 			break
diff --git a/upstream.go b/upstream.go
index d085402..47b717b 100644
--- a/upstream.go
+++ b/upstream.go
@@ -35,7 +35,6 @@ func queryUpstream(msg *dns.Msg, upstream *url.URL) (*dns.Msg, error) {
 }
 
 func queryUpstreamUDP(msg *dns.Msg, upstream *url.URL) (*dns.Msg, error) {
-	log.Debugln("query upstream", upstream.String())
 	m, _, err := dnsClientUDP.Exchange(msg, upstream.Host)
 	if err != nil {
 		log.Debugf("query udp error %s", err)
@@ -44,7 +43,6 @@ func queryUpstreamUDP(msg *dns.Msg, upstream *url.URL) (*dns.Msg, error) {
 }
 
 func queryUpstreamTCP(msg *dns.Msg, upstream *url.URL) (*dns.Msg, error) {
-	log.Debugln("query upstream", upstream.String())
 	m, _, err := dnsClientTCP.Exchange(msg, upstream.Host)
 	if err != nil {
 		log.Debugf("query tcp error %s", err)
@@ -53,7 +51,6 @@ func queryUpstreamTCP(msg *dns.Msg, upstream *url.URL) (*dns.Msg, error) {
 }
 
 func queryUpstreamTLS(msg *dns.Msg, upstream *url.URL) (*dns.Msg, error) {
-	log.Debugln("query upstream", upstream.String())
 	m, _, err := dnsClientTLS.Exchange(msg, upstream.Host)
 	if err != nil {
 		log.Debugf("query tls error %s", err)
@@ -62,7 +59,6 @@ func queryUpstreamTLS(msg *dns.Msg, upstream *url.URL) (*dns.Msg, error) {
 }
 
 func queryUpstreamHTTPS(msg *dns.Msg, upstream *url.URL) (*dns.Msg, error) {
-	log.Debugln("query upstream", upstream.String())
 	m, _, err := dnsClientHTTPS.Exchange(msg, upstream.String())
 	if err != nil {
 		log.Debugf("query https error %s", err)