diff --git a/pom.xml b/pom.xml
index f8844ec7c..73015a137 100644
--- a/pom.xml
+++ b/pom.xml
@@ -6,7 +6,7 @@
 
     <groupId>com.xceptance</groupId>
     <artifactId>xlt</artifactId>
-    <version>6.1.0</version>
+    <version>6.1.1</version>
     <packaging>jar</packaging>
 
     <name>XLT</name>
@@ -257,7 +257,7 @@
         <dependency>
             <groupId>dnsjava</groupId>
             <artifactId>dnsjava</artifactId>
-            <version>2.1.9</version>
+            <version>3.5.0</version>
         </dependency>
         <dependency>
             <groupId>com.caucho</groupId>
diff --git a/src/main/java/com/xceptance/xlt/api/webdriver/XltChromeDriver.java b/src/main/java/com/xceptance/xlt/api/webdriver/XltChromeDriver.java
index 5f0435a1b..0aea8b3f3 100644
--- a/src/main/java/com/xceptance/xlt/api/webdriver/XltChromeDriver.java
+++ b/src/main/java/com/xceptance/xlt/api/webdriver/XltChromeDriver.java
@@ -17,6 +17,7 @@
 
 import java.io.File;
 import java.net.URL;
+import java.util.Map;
 
 import org.apache.commons.io.FileUtils;
 import org.apache.commons.lang3.ObjectUtils;
@@ -362,7 +363,7 @@ private static ChromeDriverService modifyService(ChromeDriverService service, fi
                 // HACK: we can access the service's environment settings via reflection only
 
                 // read the environment settings
-                final ImmutableMap<String, String> environment = ReflectionUtils.readField(ChromeDriverService.class, service,
+                final Map<String, String> environment = ReflectionUtils.readField(ChromeDriverService.class, service,
                                                                                            FIELD_NAME_ENVIRONMENT);
 
                 // create the new environment settings including the DISPLAY variable
diff --git a/src/main/java/com/xceptance/xlt/api/webdriver/XltFirefoxDriver.java b/src/main/java/com/xceptance/xlt/api/webdriver/XltFirefoxDriver.java
index 4f1ea17af..41197b156 100644
--- a/src/main/java/com/xceptance/xlt/api/webdriver/XltFirefoxDriver.java
+++ b/src/main/java/com/xceptance/xlt/api/webdriver/XltFirefoxDriver.java
@@ -17,6 +17,7 @@
 
 import java.io.File;
 import java.net.URL;
+import java.util.Map;
 
 import org.apache.commons.io.FileUtils;
 import org.apache.commons.lang3.ObjectUtils;
@@ -416,7 +417,7 @@ private static DriverService modifyService(final DriverService service, final bo
                  */
 
                 // read the environment settings
-                final ImmutableMap<String, String> environment = ReflectionUtils.readField(DriverService.class, service,
+                final Map<String, String> environment = ReflectionUtils.readField(DriverService.class, service,
                                                                                            FIELD_NAME_ENVIRONMENT);
 
                 // create the new environment settings including the DISPLAY variable
diff --git a/src/main/java/com/xceptance/xlt/engine/dns/DnsJavaHostNameResolver.java b/src/main/java/com/xceptance/xlt/engine/dns/DnsJavaHostNameResolver.java
index 491ce33f4..79df3702f 100644
--- a/src/main/java/com/xceptance/xlt/engine/dns/DnsJavaHostNameResolver.java
+++ b/src/main/java/com/xceptance/xlt/engine/dns/DnsJavaHostNameResolver.java
@@ -17,8 +17,8 @@
 
 import java.net.InetAddress;
 import java.net.UnknownHostException;
+import java.time.Duration;
 
-import org.apache.commons.lang3.ArrayUtils;
 import org.apache.commons.lang3.StringUtils;
 import org.xbill.DNS.AAAARecord;
 import org.xbill.DNS.ARecord;
@@ -69,7 +69,7 @@ class DnsJavaHostNameResolver implements HostNameResolver
             final String[] serverAddresses = StringUtils.split(dnsServers, "\t ,;");
             resolver = (serverAddresses.length == 0) ? new ExtendedResolver() : new ExtendedResolver(serverAddresses);
 
-            resolver.setTimeout(timeoutSeconds);
+            resolver.setTimeout(Duration.ofSeconds(timeoutSeconds));
 
             if (ednsVersion >= 0)
             {
@@ -132,7 +132,7 @@ private Record[] lookupRecordsByHostName(final String name) throws UnknownHostEx
             final Record[] a = createNewLookup(name, Type.A).run();
             final Record[] aaaa = createNewLookup(name, Type.AAAA).run();
 
-            final Record[] merged = ArrayUtils.addAll(a, aaaa);
+            final Record[] merged = concatRecordArrays(a, aaaa);
             if (merged == null)
             {
                 throw new UnknownHostException("Unknown host: " + name);
@@ -146,6 +146,43 @@ private Record[] lookupRecordsByHostName(final String name) throws UnknownHostEx
         }
     }
 
+    /**
+     * Concatenates the given {@link Record} arrays, handling <code>null</code> arrays sensibly.
+     * 
+     * @param a
+     *            the A records (may be <code>null</code>)
+     * @param aaaa
+     *            the AAAA records (may be <code>null</code>)
+     * @return <code>null</code> if both input arrays were <code>null</code>, a result {@link Record} array otherwise
+     */
+    private Record[] concatRecordArrays(final Record[] a, final Record[] aaaa)
+    {
+        /*
+         * Replaces "ArrayUtils.addAll(a, aaaa)" which cannot handle arrays of different sub-types, i.e. ARecord[] and
+         * AAAARecord[].
+         */
+
+        final Record[] combined;
+
+        if (a == null)
+        {
+            combined = aaaa;
+        }
+        else if (aaaa == null)
+        {
+            combined = a;
+        }
+        else
+        {
+            combined = new Record[a.length + aaaa.length];
+
+            System.arraycopy(a, 0, combined, 0, a.length);
+            System.arraycopy(aaaa, 0, combined, a.length, aaaa.length);
+        }
+
+        return combined;
+    }
+
     /**
      * Creates a new {@link Lookup} instance for the given host name and query type and customizes it a bit.
      */