diff --git a/nasType/NAS_DNN.go b/nasType/NAS_DNN.go
index f76c3b1..5e7359d 100644
--- a/nasType/NAS_DNN.go
+++ b/nasType/NAS_DNN.go
@@ -65,15 +65,17 @@ func fqdnToRfc1035(fqdn string) ([]byte, error) {
 	domainSegments := strings.Split(fqdn, ".")
 
 	for _, segment := range domainSegments {
-		if len(segment) > 63 {
-			return nil, errors.New("fqdn limit the label to 63 octets or less")
+		// In RFC 1035 max length is 63, but in TS 23.003 including length octet
+		if len(segment) > 62 {
+			return nil, errors.New("DNN limit the label to 62 octets or less")
 		}
 		rfc1035RR = append(rfc1035RR, uint8(len(segment)))
 		rfc1035RR = append(rfc1035RR, segment...)
 	}
 
-	if len(rfc1035RR) > 255 {
-		return nil, errors.New("fqdn should less then 255 octet")
+	// In RFC 1035 max length is 255, but in TS 23.003 is 100
+	if len(rfc1035RR) > 100 {
+		return nil, errors.New("DNN should less then 100 octet")
 	}
 	return rfc1035RR, nil
 }
diff --git a/nasType/NAS_DNN_test.go b/nasType/NAS_DNN_test.go
index ad1ec9a..9f86f7c 100644
--- a/nasType/NAS_DNN_test.go
+++ b/nasType/NAS_DNN_test.go
@@ -56,13 +56,49 @@ func TestNasTypeDNNGetSetDNNValue(t *testing.T) {
 				0x03, 0x63, 0x6f, 0x6d,
 			},
 		},
+		{
+			// length of label = 62, length of encoded buffer = 100
+			"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789" +
+				".ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghij",
+			[]uint8{0x3E,
+				0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49,
+				0x4A, 0x4B, 0x4C, 0x4D, 0x4E, 0x4F, 0x50, 0x51, 0x52,
+				0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5A,
+				0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69,
+				0x6A, 0x6B, 0x6C, 0x6D, 0x6E, 0x6F, 0x70, 0x71, 0x72,
+				0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7A,
+				0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39,
+				0x24,
+				0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49,
+				0x4A, 0x4B, 0x4C, 0x4D, 0x4E, 0x4F, 0x50, 0x51, 0x52,
+				0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5A,
+				0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6A,
+			},
+		},
 	}
 
 	a := nasType.NewDNN(0)
 	for _, table := range NNTable {
 		a.SetDNN(table.in)
 		assert.Equalf(t, table.out, a.Buffer, "in(%v): out %v, actual %x", table.in, table.out, a.Buffer)
-		assert.Equalf(t, uint8(len(table.out)), a.Len, "outlen %d, actual %d", table.in, len(table.out), a.Len)
+		assert.Equalf(t, uint8(len(table.out)), a.Len, "in(%v): outlen %d, actual %d", table.in, len(table.out), a.Len)
 		assert.Equalf(t, table.in, a.GetDNN(), "in(%v): GetDNN %x", table.in, a.GetDNN())
 	}
 }
+
+func TestNasTypeDNNSetDNNInvalidValue(t *testing.T) {
+	invalidDnns := []string{
+		// length of label > 62
+		"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789A",
+		// length of encoded buffer > 100
+		"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789.ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijk",
+	}
+
+	var emptyDNN []uint8
+	a := nasType.NewDNN(0)
+	for _, dnn := range invalidDnns {
+		a.SetDNN(dnn)
+		assert.Equalf(t, emptyDNN, a.Buffer, "in(%v): out <>, actual %x", dnn, a.Buffer)
+		assert.Equalf(t, uint8(0), a.Len, "in(%v): outlen 0, actual %d", dnn, a.Len)
+	}
+}