diff --git a/CHANGES.md b/CHANGES.md
index 9a9a1373c..da4bce33a 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -4,6 +4,7 @@ Future
 * [PR#196](https://github.com/kaitoy/pcap4j/pull/196): add protocol implementations for 4 icmpv6 types (RFC6275).
 
 ### Bug Fixes ###
+* [Issues#200](https://github.com/kaitoy/pcap4j/issues/200): Fix a bug that causes NullPointerException in DnsDomainName#toString(byte[]).
 
 ### Other Changes ###
 
diff --git a/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataCName.java b/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataCName.java
index bcafc851c..defe980fb 100644
--- a/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataCName.java
+++ b/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataCName.java
@@ -1,6 +1,6 @@
 /*_##########################################################################
   _##
-  _##  Copyright (C) 2016  Pcap4J.org
+  _##  Copyright (C) 2016-2019  Pcap4J.org
   _##
   _##########################################################################
 */
@@ -113,7 +113,7 @@ private String convertToString(String indent, byte[] headerRawData) {
         .append(ls)
         .append(indent)
         .append("  CNAME: ")
-        .append(cName.toString(headerRawData))
+        .append(headerRawData != null ? cName.toString(headerRawData) : cName.toString())
         .append(ls);
 
     return sb.toString();
diff --git a/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataMInfo.java b/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataMInfo.java
index 56761f61e..9c2a3c562 100644
--- a/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataMInfo.java
+++ b/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataMInfo.java
@@ -1,6 +1,6 @@
 /*_##########################################################################
   _##
-  _##  Copyright (C) 2016  Pcap4J.org
+  _##  Copyright (C) 2016-2019  Pcap4J.org
   _##
   _##########################################################################
 */
@@ -162,11 +162,11 @@ private String convertToString(String indent, byte[] headerRawData) {
         .append(ls)
         .append(indent)
         .append("  RMAILBX: ")
-        .append(rMailBx.toString(headerRawData))
+        .append(headerRawData != null ? rMailBx.toString(headerRawData) : rMailBx.toString())
         .append(ls)
         .append(indent)
         .append("  EMAILBX: ")
-        .append(eMailBx.toString(headerRawData))
+        .append(headerRawData != null ? eMailBx.toString(headerRawData) : eMailBx.toString())
         .append(ls);
 
     return sb.toString();
diff --git a/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataMb.java b/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataMb.java
index 5660d978c..ad9c86b1e 100644
--- a/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataMb.java
+++ b/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataMb.java
@@ -1,6 +1,6 @@
 /*_##########################################################################
   _##
-  _##  Copyright (C) 2016  Pcap4J.org
+  _##  Copyright (C) 2016-2019  Pcap4J.org
   _##
   _##########################################################################
 */
@@ -111,7 +111,7 @@ private String convertToString(String indent, byte[] headerRawData) {
         .append(ls)
         .append(indent)
         .append("  MADNAME: ")
-        .append(maDName.toString(headerRawData))
+        .append(headerRawData != null ? maDName.toString(headerRawData) : maDName.toString())
         .append(ls);
 
     return sb.toString();
diff --git a/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataMd.java b/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataMd.java
index 16ecd5c37..764bc95fe 100644
--- a/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataMd.java
+++ b/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataMd.java
@@ -1,6 +1,6 @@
 /*_##########################################################################
   _##
-  _##  Copyright (C) 2016  Pcap4J.org
+  _##  Copyright (C) 2016-2019  Pcap4J.org
   _##
   _##########################################################################
 */
@@ -114,7 +114,7 @@ private String convertToString(String indent, byte[] headerRawData) {
         .append(ls)
         .append(indent)
         .append("  MADNAME: ")
-        .append(maDName.toString(headerRawData))
+        .append(headerRawData != null ? maDName.toString(headerRawData) : maDName.toString())
         .append(ls);
 
     return sb.toString();
diff --git a/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataMf.java b/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataMf.java
index ba52a49b5..c235794e9 100644
--- a/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataMf.java
+++ b/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataMf.java
@@ -1,6 +1,6 @@
 /*_##########################################################################
   _##
-  _##  Copyright (C) 2016  Pcap4J.org
+  _##  Copyright (C) 2016-2019  Pcap4J.org
   _##
   _##########################################################################
 */
@@ -114,7 +114,7 @@ private String convertToString(String indent, byte[] headerRawData) {
         .append(ls)
         .append(indent)
         .append("  MADNAME: ")
-        .append(maDName.toString(headerRawData))
+        .append(headerRawData != null ? maDName.toString(headerRawData) : maDName.toString())
         .append(ls);
 
     return sb.toString();
diff --git a/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataMg.java b/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataMg.java
index edcd25444..0661a7245 100644
--- a/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataMg.java
+++ b/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataMg.java
@@ -1,6 +1,6 @@
 /*_##########################################################################
   _##
-  _##  Copyright (C) 2016  Pcap4J.org
+  _##  Copyright (C) 2016-2019  Pcap4J.org
   _##
   _##########################################################################
 */
@@ -113,7 +113,7 @@ private String convertToString(String indent, byte[] headerRawData) {
         .append(ls)
         .append(indent)
         .append("  MGMNAME: ")
-        .append(mgMName.toString(headerRawData))
+        .append(headerRawData != null ? mgMName.toString(headerRawData) : mgMName.toString())
         .append(ls);
 
     return sb.toString();
diff --git a/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataMr.java b/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataMr.java
index fb42de63f..5b2de7ca8 100644
--- a/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataMr.java
+++ b/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataMr.java
@@ -1,6 +1,6 @@
 /*_##########################################################################
   _##
-  _##  Copyright (C) 2016  Pcap4J.org
+  _##  Copyright (C) 2016-2019  Pcap4J.org
   _##
   _##########################################################################
 */
@@ -113,7 +113,7 @@ private String convertToString(String indent, byte[] headerRawData) {
         .append(ls)
         .append(indent)
         .append("  NEWNAME: ")
-        .append(newName.toString(headerRawData))
+        .append(headerRawData != null ? newName.toString(headerRawData) : newName.toString())
         .append(ls);
 
     return sb.toString();
diff --git a/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataMx.java b/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataMx.java
index 453a70203..897d102d7 100644
--- a/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataMx.java
+++ b/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataMx.java
@@ -1,6 +1,6 @@
 /*_##########################################################################
   _##
-  _##  Copyright (C) 2016  Pcap4J.org
+  _##  Copyright (C) 2016-2019  Pcap4J.org
   _##
   _##########################################################################
 */
@@ -157,7 +157,7 @@ private String convertToString(String indent, byte[] headerRawData) {
         .append(ls)
         .append(indent)
         .append("  EXCHANGE: ")
-        .append(exchange.toString(headerRawData))
+        .append(headerRawData != null ? exchange.toString(headerRawData) : exchange.toString())
         .append(ls);
 
     return sb.toString();
diff --git a/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataNs.java b/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataNs.java
index f7a0afe01..a3f2fc6be 100644
--- a/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataNs.java
+++ b/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataNs.java
@@ -1,6 +1,6 @@
 /*_##########################################################################
   _##
-  _##  Copyright (C) 2016  Pcap4J.org
+  _##  Copyright (C) 2016-2019  Pcap4J.org
   _##
   _##########################################################################
 */
@@ -113,7 +113,7 @@ private String convertToString(String indent, byte[] headerRawData) {
         .append(ls)
         .append(indent)
         .append("  NSDNAME: ")
-        .append(nsDName.toString(headerRawData))
+        .append(headerRawData != null ? nsDName.toString(headerRawData) : nsDName.toString())
         .append(ls);
 
     return sb.toString();
diff --git a/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataPtr.java b/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataPtr.java
index e1dc9f1eb..125154456 100644
--- a/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataPtr.java
+++ b/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataPtr.java
@@ -1,6 +1,6 @@
 /*_##########################################################################
   _##
-  _##  Copyright (C) 2016  Pcap4J.org
+  _##  Copyright (C) 2016-2019  Pcap4J.org
   _##
   _##########################################################################
 */
@@ -113,7 +113,7 @@ private String convertToString(String indent, byte[] headerRawData) {
         .append(ls)
         .append(indent)
         .append("  PTRDNAME: ")
-        .append(ptrDName.toString(headerRawData))
+        .append(headerRawData != null ? ptrDName.toString(headerRawData) : ptrDName.toString())
         .append(ls);
 
     return sb.toString();
diff --git a/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataSoa.java b/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataSoa.java
index 8b89ecf59..58d26523b 100644
--- a/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataSoa.java
+++ b/pcap4j-core/src/main/java/org/pcap4j/packet/DnsRDataSoa.java
@@ -1,6 +1,6 @@
 /*_##########################################################################
   _##
-  _##  Copyright (C) 2016  Pcap4J.org
+  _##  Copyright (C) 2016-2019  Pcap4J.org
   _##
   _##########################################################################
 */
@@ -287,11 +287,11 @@ private String convertToString(String indent, byte[] headerRawData) {
         .append(ls)
         .append(indent)
         .append("  MNAME: ")
-        .append(mName.toString(headerRawData))
+        .append(headerRawData != null ? mName.toString(headerRawData) : mName.toString())
         .append(ls)
         .append(indent)
         .append("  RNAME: ")
-        .append(rName.toString(headerRawData))
+        .append(headerRawData != null ? rName.toString(headerRawData) : rName.toString())
         .append(ls)
         .append(indent)
         .append("  SERIAL: ")
diff --git a/pcap4j-packettest/src/test/java/org/pcap4j/packet/DnsPacketTest.java b/pcap4j-packettest/src/test/java/org/pcap4j/packet/DnsPacketTest.java
index 2f8f05697..889a072b5 100644
--- a/pcap4j-packettest/src/test/java/org/pcap4j/packet/DnsPacketTest.java
+++ b/pcap4j-packettest/src/test/java/org/pcap4j/packet/DnsPacketTest.java
@@ -584,4 +584,17 @@ public void testNewPacket() {
       throw new AssertionError(e);
     }
   }
+
+  @Test
+  public void testToString() {
+    for (DnsResourceRecord r : packet.getHeader().getAnswers()) {
+      logger.info(r.toString());
+    }
+    for (DnsResourceRecord r : packet.getHeader().getAuthorities()) {
+      logger.info(r.toString());
+    }
+    for (DnsResourceRecord r : packet.getHeader().getAdditionalInfo()) {
+      logger.info(r.toString());
+    }
+  }
 }