diff --git a/component/control/bpf_utils.go b/component/control/bpf_utils.go
index b2540ac..3b4bff1 100644
--- a/component/control/bpf_utils.go
+++ b/component/control/bpf_utils.go
@@ -18,6 +18,7 @@ import (
 	"os"
 	"reflect"
 	"strings"
+	"sync"
 )
 
 type _bpfLpmKey struct {
@@ -67,16 +68,22 @@ func cidrToBpfLpmKey(prefix netip.Prefix) _bpfLpmKey {
 	}
 }
 
+var (
+	CheckBatchUpdateFeatureOnce sync.Once
+	SimulateBatchUpdate         bool
+)
+
 func BatchUpdate(m *ebpf.Map, keys interface{}, values interface{}, opts *ebpf.BatchOptions) (n int, err error) {
-	var old bool
-	version, e := internal.KernelVersion()
-	if e != nil || version.Less(consts.UserspaceBatchUpdateFeatureVersion) {
-		old = true
-	}
-	if m.Type() == ebpf.LPMTrie && version.Less(consts.UserspaceBatchUpdateLpmTrieFeatureVersion) {
-		old = true
-	}
-	if !old {
+	CheckBatchUpdateFeatureOnce.Do(func() {
+		version, e := internal.KernelVersion()
+		if e != nil || version.Less(consts.UserspaceBatchUpdateFeatureVersion) {
+			SimulateBatchUpdate = true
+		}
+		if m.Type() == ebpf.LPMTrie && version.Less(consts.UserspaceBatchUpdateLpmTrieFeatureVersion) {
+			SimulateBatchUpdate = true
+		}
+	})
+	if !SimulateBatchUpdate {
 		return m.BatchUpdate(keys, values, opts)
 	} else {
 		vKeys := reflect.ValueOf(keys)
diff --git a/component/control/control_plane.go b/component/control/control_plane.go
index da0ee65..7116627 100644
--- a/component/control/control_plane.go
+++ b/component/control/control_plane.go
@@ -90,7 +90,7 @@ func NewControlPlane(
 	log.Infof("Loading eBPF programs and maps into the kernel")
 	var bpf bpfObjects
 	var ProgramOptions ebpf.ProgramOptions
-	if log.IsLevelEnabled(logrus.TraceLevel) {
+	if log.Level == logrus.PanicLevel {
 		ProgramOptions = ebpf.ProgramOptions{
 			LogLevel: ebpf.LogLevelBranch | ebpf.LogLevelStats,
 			//LogLevel: ebpf.LogLevelInstruction | ebpf.LogLevelStats,
@@ -127,11 +127,11 @@ retryLoadBpf:
 			goto retryLoadBpf
 		}
 		// Get detailed log from ebpf.internal.(*VerifierError)
-		if log.IsLevelEnabled(logrus.TraceLevel) {
+		if log.Level == logrus.PanicLevel {
 			if v := reflect.Indirect(reflect.ValueOf(errors.Unwrap(errors.Unwrap(err)))); v.Kind() == reflect.Struct {
 				if _log := v.FieldByName("Log"); _log.IsValid() {
 					if strSlice, ok := _log.Interface().([]string); ok {
-						log.Traceln(strings.Join(strSlice, "\n"))
+						log.Panicln(strings.Join(strSlice, "\n"))
 					}
 				}
 			}
diff --git a/component/control/dns.go b/component/control/dns.go
index 9b10733..71d6c04 100644
--- a/component/control/dns.go
+++ b/component/control/dns.go
@@ -9,6 +9,8 @@ import (
 	"encoding/binary"
 	"fmt"
 	"github.com/cilium/ebpf"
+	"github.com/mohae/deepcopy"
+	"github.com/sirupsen/logrus"
 	"github.com/v2rayA/dae/common"
 	"github.com/v2rayA/dae/common/consts"
 	"golang.org/x/net/dns/dnsmessage"
@@ -26,7 +28,15 @@ type dnsCache struct {
 }
 
 func (c *dnsCache) FillInto(req *dnsmessage.Message) {
-	req.Answers = c.Answers
+	req.Answers = deepcopy.Copy(c.Answers).([]dnsmessage.Resource)
+	// 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
+		}
+	}
 	req.RCode = dnsmessage.RCodeSuccess
 	req.Response = true
 	req.RecursionAvailable = true
@@ -137,9 +147,8 @@ func (c *ControlPlane) DnsRespHandler(data []byte) (newData []byte, err error) {
 		return data, nil
 	}
 	q := msg.Questions[0]
-	// If first answer is CNAME type, replace the Name with flipping-backed Name.
+	// Align question and answer Name.
 	if len(msg.Answers) > 0 &&
-		msg.Answers[0].Header.Type == dnsmessage.TypeCNAME &&
 		strings.EqualFold(msg.Answers[0].Header.Name.String(), q.Name.String()) {
 		msg.Answers[0].Header.Name.Data = q.Name.Data
 	}
@@ -174,6 +183,10 @@ func (c *ControlPlane) DnsRespHandler(data []byte) (newData []byte, err error) {
 	}
 
 	// Update dnsCache.
+	c.log.WithFields(logrus.Fields{
+		"qname": q.Name,
+		"ans":   msg.Answers,
+	}).Tracef("Update DNS record cache")
 	c.mutex.Lock()
 	fqdn := strings.ToLower(q.Name.String())
 	cacheKey := fqdn + q.Type.String()
diff --git a/example.dae b/example.dae
index 8abc817..81cca35 100644
--- a/example.dae
+++ b/example.dae
@@ -8,6 +8,7 @@ global {
 
     # Now only support UDP and IP:Port.
     # Please make sure DNS traffic will go through and be forwarded by dae.
+    # The upstream DNS answer MUST NOT be polluted.
     # The request to dns upstream follows routing defined below.
     dns_upstream: '8.8.8.8:53'
 
@@ -62,7 +63,7 @@ group {
 routing {
     # See routing.md for full examples.
 
-    ip(8.8.8.8) && port(53) -> direct
+    ip(8.8.8.8, 1.1.1.1) && port(53) -> my_group
 
     pname(firefox) && domain(ip.sb) -> direct
     pname(curl) && domain(ip.sb) -> my_group