diff --git a/serve.go b/serve.go
index 34d7180..be60178 100644
--- a/serve.go
+++ b/serve.go
@@ -315,7 +315,7 @@ func (handler *dnsRequestHandler) ServeDNS(responseWriter dnsprotocol.ResponseWr
 		if !found {
 			goto noRecord
 		}
-		for _, value := range record.A {
+		for _, value := range normalizeRecordValues(record.A) {
 			parsedIP := net.ParseIP(value)
 			if parsedIP == nil || parsedIP.To4() == nil {
 				continue
@@ -329,7 +329,7 @@ func (handler *dnsRequestHandler) ServeDNS(responseWriter dnsprotocol.ResponseWr
 		if !found {
 			goto noRecord
 		}
-		for _, value := range record.AAAA {
+		for _, value := range normalizeRecordValues(record.AAAA) {
 			parsedIP := net.ParseIP(value)
 			if parsedIP == nil || parsedIP.To4() != nil {
 				continue
@@ -343,7 +343,7 @@ func (handler *dnsRequestHandler) ServeDNS(responseWriter dnsprotocol.ResponseWr
 		if !found {
 			goto noRecord
 		}
-		for _, value := range record.TXT {
+		for _, value := range normalizeRecordValues(record.TXT) {
 			reply.Answer = append(reply.Answer, &dnsprotocol.TXT{
 				Hdr: dnsprotocol.RR_Header{Name: question.Name, Rrtype: dnsprotocol.TypeTXT, Class: dnsprotocol.ClassINET, Ttl: defaultDNSTTL},
 				Txt: []string{value},
@@ -351,7 +351,7 @@ func (handler *dnsRequestHandler) ServeDNS(responseWriter dnsprotocol.ResponseWr
 		}
 	case dnsprotocol.TypeNS:
 		if found {
-			for _, value := range record.NS {
+			for _, value := range normalizeRecordValues(record.NS) {
 				reply.Answer = append(reply.Answer, &dnsprotocol.NS{
 					Hdr: dnsprotocol.RR_Header{Name: question.Name, Rrtype: dnsprotocol.TypeNS, Class: dnsprotocol.ClassINET, Ttl: defaultDNSTTL},
 					Ns:  normalizeName(value) + ".",
@@ -413,17 +413,17 @@ func (handler *dnsRequestHandler) ServeDNS(responseWriter dnsprotocol.ResponseWr
 		if !found {
 			goto noRecord
 		}
-		appendDNSSECResourceRecords(reply, question.Name, dnsprotocol.TypeDS, record.DS)
+		appendDNSSECResourceRecords(reply, question.Name, dnsprotocol.TypeDS, normalizeRecordValues(record.DS))
 	case dnsprotocol.TypeDNSKEY:
 		if !found {
 			goto noRecord
 		}
-		appendDNSSECResourceRecords(reply, question.Name, dnsprotocol.TypeDNSKEY, record.DNSKEY)
+		appendDNSSECResourceRecords(reply, question.Name, dnsprotocol.TypeDNSKEY, normalizeRecordValues(record.DNSKEY))
 	case dnsprotocol.TypeRRSIG:
 		if !found {
 			goto noRecord
 		}
-		appendDNSSECResourceRecords(reply, question.Name, dnsprotocol.TypeRRSIG, record.RRSIG)
+		appendDNSSECResourceRecords(reply, question.Name, dnsprotocol.TypeRRSIG, normalizeRecordValues(record.RRSIG))
 	default:
 		reply.SetRcode(request, dnsprotocol.RcodeNotImplemented)
 		_ = responseWriter.WriteMsg(reply)
@@ -496,7 +496,7 @@ func parsePTRIP(name string) (string, bool) {
 }
 
 func appendAnyAnswers(reply *dnsprotocol.Msg, questionName string, lookupName string, record NameRecords, zoneApex string) {
-	for _, value := range record.A {
+	for _, value := range normalizeRecordValues(record.A) {
 		parsedIP := net.ParseIP(value)
 		if parsedIP == nil || parsedIP.To4() == nil {
 			continue
@@ -507,7 +507,7 @@ func appendAnyAnswers(reply *dnsprotocol.Msg, questionName string, lookupName st
 		})
 	}
 
-	for _, value := range record.AAAA {
+	for _, value := range normalizeRecordValues(record.AAAA) {
 		parsedIP := net.ParseIP(value)
 		if parsedIP == nil || parsedIP.To4() != nil {
 			continue
@@ -518,7 +518,7 @@ func appendAnyAnswers(reply *dnsprotocol.Msg, questionName string, lookupName st
 		})
 	}
 
-	for _, value := range record.TXT {
+	for _, value := range normalizeRecordValues(record.TXT) {
 		reply.Answer = append(reply.Answer, &dnsprotocol.TXT{
 			Hdr: dnsprotocol.RR_Header{Name: questionName, Rrtype: dnsprotocol.TypeTXT, Class: dnsprotocol.ClassINET, Ttl: defaultDNSTTL},
 			Txt: []string{value},
@@ -526,7 +526,7 @@ func appendAnyAnswers(reply *dnsprotocol.Msg, questionName string, lookupName st
 	}
 
 	if len(record.NS) > 0 {
-		for _, value := range record.NS {
+		for _, value := range normalizeRecordValues(record.NS) {
 			reply.Answer = append(reply.Answer, &dnsprotocol.NS{
 				Hdr: dnsprotocol.RR_Header{Name: questionName, Rrtype: dnsprotocol.TypeNS, Class: dnsprotocol.ClassINET, Ttl: defaultDNSTTL},
 				Ns:  normalizeName(value) + ".",
@@ -534,15 +534,15 @@ func appendAnyAnswers(reply *dnsprotocol.Msg, questionName string, lookupName st
 		}
 	}
 
-	for _, value := range record.DNSKEY {
+	for _, value := range normalizeRecordValues(record.DNSKEY) {
 		appendDNSSECResourceRecords(reply, questionName, dnsprotocol.TypeDNSKEY, []string{value})
 	}
 
-	for _, value := range record.DS {
+	for _, value := range normalizeRecordValues(record.DS) {
 		appendDNSSECResourceRecords(reply, questionName, dnsprotocol.TypeDS, []string{value})
 	}
 
-	for _, value := range record.RRSIG {
+	for _, value := range normalizeRecordValues(record.RRSIG) {
 		appendDNSSECResourceRecords(reply, questionName, dnsprotocol.TypeRRSIG, []string{value})
 	}
 
diff --git a/service.go b/service.go
index 4f1f3b3..406ce51 100644
--- a/service.go
+++ b/service.go
@@ -994,13 +994,13 @@ func (service *Service) findRecordWithMatch(name string) (NameRecords, bool, boo
 
 func resolveResult(record NameRecords) ResolveAllResult {
 	return ResolveAllResult{
-		A:      cloneStrings(record.A),
-		AAAA:   cloneStrings(record.AAAA),
-		TXT:    cloneStrings(record.TXT),
-		NS:     cloneStrings(record.NS),
-		DS:     cloneStrings(record.DS),
-		DNSKEY: cloneStrings(record.DNSKEY),
-		RRSIG:  cloneStrings(record.RRSIG),
+		A:      normalizeRecordValues(record.A),
+		AAAA:   normalizeRecordValues(record.AAAA),
+		TXT:    normalizeRecordValues(record.TXT),
+		NS:     normalizeRecordValues(record.NS),
+		DS:     normalizeRecordValues(record.DS),
+		DNSKEY: normalizeRecordValues(record.DNSKEY),
+		RRSIG:  normalizeRecordValues(record.RRSIG),
 	}
 }
 
@@ -1136,9 +1136,30 @@ func computeZoneApex(records map[string]NameRecords) string {
 }
 
 func serializeRecordValues(values []string) string {
-	copied := append([]string(nil), values...)
-	slices.Sort(copied)
-	return strings.Join(copied, ",")
+	normalized := normalizeRecordValues(values)
+	return strings.Join(normalized, ",")
+}
+
+func normalizeRecordValues(values []string) []string {
+	if len(values) == 0 {
+		return []string{}
+	}
+
+	seen := make(map[string]struct{}, len(values))
+	normalized := make([]string, 0, len(values))
+	for _, value := range values {
+		if value == "" {
+			continue
+		}
+		if _, exists := seen[value]; exists {
+			continue
+		}
+		seen[value] = struct{}{}
+		normalized = append(normalized, value)
+	}
+
+	slices.Sort(normalized)
+	return normalized
 }
 
 func cloneStrings(values []string) []string {
@@ -1231,17 +1252,9 @@ func (service *Service) String() string {
 //
 //	values := MergeRecords([]string{"10.10.10.10"}, []string{"10.0.0.1", "10.10.10.10"})
 func MergeRecords(values ...[]string) []string {
-	unique := []string{}
-	seen := map[string]bool{}
+	merged := []string{}
 	for _, batch := range values {
-		for _, value := range batch {
-			if seen[value] {
-				continue
-			}
-			seen[value] = true
-			unique = append(unique, value)
-		}
+		merged = append(merged, batch...)
 	}
-	slices.Sort(unique)
-	return unique
+	return normalizeRecordValues(merged)
 }