diff --git a/cmd/internal/subscription.go b/cmd/internal/subscription.go
index a3226ae..721067e 100644
--- a/cmd/internal/subscription.go
+++ b/cmd/internal/subscription.go
@@ -81,6 +81,15 @@ func resolveSubscriptionAsSIP008(log *logrus.Logger, b []byte) (nodes []string,
 }
 
 func ResolveSubscription(log *logrus.Logger, subscription string) (nodes []string, err error) {
+	u, err := url.Parse(subscription)
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse subscription \"%v\": %w", subscription, err)
+	}
+	switch u.Scheme {
+	case "file":
+		// TODO
+	default:
+	}
 	log.Debugf("ResolveSubscription: %v", subscription)
 	resp, err := http.Get(subscription)
 	if err != nil {
diff --git a/control/bpf_utils.go b/control/bpf_utils.go
index dafeaa4..05de0fe 100644
--- a/control/bpf_utils.go
+++ b/control/bpf_utils.go
@@ -50,7 +50,7 @@ func (o *bpfObjects) newLpmMap(keys []_bpfLpmKey, values []uint32) (m *ebpf.Map,
 	if err != nil {
 		return nil, err
 	}
-	if _, err = BatchUpdate(m, keys, values, &ebpf.BatchOptions{
+	if _, err = BpfMapBatchUpdate(m, keys, values, &ebpf.BatchOptions{
 		ElemFlags: uint64(ebpf.UpdateAny),
 	}); err != nil {
 		return nil, err
@@ -76,7 +76,7 @@ var (
 	SimulateBatchUpdateLpmTrie  bool
 )
 
-func BatchUpdate(m *ebpf.Map, keys interface{}, values interface{}, opts *ebpf.BatchOptions) (n int, err error) {
+func BpfMapBatchUpdate(m *ebpf.Map, keys interface{}, values interface{}, opts *ebpf.BatchOptions) (n int, err error) {
 	CheckBatchUpdateFeatureOnce.Do(func() {
 		version, e := internal.KernelVersion()
 		if e != nil {
@@ -98,7 +98,7 @@ func BatchUpdate(m *ebpf.Map, keys interface{}, values interface{}, opts *ebpf.B
 	}
 
 	if !simulate {
-		// Genuine BatchUpdate
+		// Genuine BpfMapBatchUpdate
 		return m.BatchUpdate(keys, values, opts)
 	}
 
diff --git a/control/dns.go b/control/dns.go
index f222fe9..7096ba5 100644
--- a/control/dns.go
+++ b/control/dns.go
@@ -38,9 +38,10 @@ func (c *dnsCache) FillInto(req *dnsmessage.Message) {
 	// Align question and answer Name.
 	if len(req.Questions) > 0 {
 		q := req.Questions[0]
-		if len(req.Answers) > 0 &&
-			strings.EqualFold(req.Answers[0].Header.Name.String(), q.Name.String()) {
-			req.Answers[0].Header.Name.Data = q.Name.Data
+		for i := range req.Answers {
+			if strings.EqualFold(req.Answers[i].Header.Name.String(), q.Name.String()) {
+				req.Answers[i].Header.Name.Data = q.Name.Data
+			}
 		}
 	}
 	req.RCode = dnsmessage.RCodeSuccess
@@ -64,7 +65,7 @@ func (c *ControlPlane) BatchUpdateDomainRouting(cache *dnsCache) error {
 	}
 
 	// Update bpf map.
-	// Construct keys and vals, and BatchUpdate.
+	// Construct keys and vals, and BpfMapBatchUpdate.
 	var keys [][4]uint32
 	var vals []bpfDomainRouting
 	for _, ip := range ips {
@@ -74,7 +75,7 @@ func (c *ControlPlane) BatchUpdateDomainRouting(cache *dnsCache) error {
 			Bitmap: cache.DomainBitmap,
 		})
 	}
-	if _, err := BatchUpdate(c.core.bpf.DomainRoutingMap, keys, vals, &ebpf.BatchOptions{
+	if _, err := BpfMapBatchUpdate(c.core.bpf.DomainRoutingMap, keys, vals, &ebpf.BatchOptions{
 		ElemFlags: uint64(ebpf.UpdateAny),
 	}); err != nil {
 		return err
@@ -205,9 +206,10 @@ func (c *ControlPlane) DnsRespHandler(data []byte, validateRushAns bool) (newDat
 	FlipDnsQuestionCase(&msg)
 	q := msg.Questions[0]
 	// Align Name.
-	if len(msg.Answers) > 0 &&
-		strings.EqualFold(msg.Answers[0].Header.Name.String(), q.Name.String()) {
-		msg.Answers[0].Header.Name.Data = q.Name.Data
+	for i := range msg.Answers {
+		if strings.EqualFold(msg.Answers[i].Header.Name.String(), q.Name.String()) {
+			msg.Answers[i].Header.Name.Data = q.Name.Data
+		}
 	}
 	for i := range msg.Additionals {
 		if strings.EqualFold(msg.Additionals[i].Header.Name.String(), q.Name.String()) {
diff --git a/control/routing_matcher_builder.go b/control/routing_matcher_builder.go
index 5196cc7..7a50c04 100644
--- a/control/routing_matcher_builder.go
+++ b/control/routing_matcher_builder.go
@@ -240,7 +240,7 @@ func (b *RoutingMatcherBuilder) Build() (err error) {
 		if err != nil {
 			return fmt.Errorf("newLpmMap: %w", err)
 		}
-		// ebpf.Map cannot be BatchUpdate
+		// We cannot invoke BpfMapBatchUpdate when value is ebpf.Map.
 		if err = b.bpf.LpmArrayMap.Update(uint32(i), m, ebpf.UpdateAny); err != nil {
 			m.Close()
 			return fmt.Errorf("Update: %w", err)
@@ -255,10 +255,10 @@ func (b *RoutingMatcherBuilder) Build() (err error) {
 	}
 	routingsLen := uint32(len(b.rules))
 	routingsKeys := common.ARangeU32(routingsLen)
-	if _, err = BatchUpdate(b.bpf.RoutingMap, routingsKeys, b.rules, &ebpf.BatchOptions{
+	if _, err = BpfMapBatchUpdate(b.bpf.RoutingMap, routingsKeys, b.rules, &ebpf.BatchOptions{
 		ElemFlags: uint64(ebpf.UpdateAny),
 	}); err != nil {
-		return fmt.Errorf("BatchUpdate: %w", err)
+		return fmt.Errorf("BpfMapBatchUpdate: %w", err)
 	}
 	return nil
 }