diff --git a/arc_dns_injector/src/main/java/git/artdeell/arcdns/ArcDNSInjectorAgent.java b/arc_dns_injector/src/main/java/git/artdeell/arcdns/ArcDNSInjectorAgent.java
index f21479feb..02d6249c2 100644
--- a/arc_dns_injector/src/main/java/git/artdeell/arcdns/ArcDNSInjectorAgent.java
+++ b/arc_dns_injector/src/main/java/git/artdeell/arcdns/ArcDNSInjectorAgent.java
@@ -5,16 +5,23 @@ public class ArcDNSInjectorAgent {
         System.out.println("Arc Capes DNS Injector");
         System.out.println("Parts of Alibaba's DCM library were used, please read https://github.com/alibaba/java-dns-cache-manipulator/blob/main/README.md for more info");
         String[] injectedIps = new String[]{args};
+
         try {
-             CacheUtil_J9.setInetAddressCache("s.optifine.net", injectedIps, CacheUtilCommons.NEVER_EXPIRATION);
+            CacheUtil_J21.setInetAddressCache("s.optifine.net", injectedIps, CacheUtilCommons.NEVER_EXPIRATION);
         } catch (Exception e) {
             try {
-                 CacheUtil_J8.setInetAddressCache("s.optifine.net", injectedIps, CacheUtilCommons.NEVER_EXPIRATION);
+                CacheUtil_J9.setInetAddressCache("s.optifine.net", injectedIps, CacheUtilCommons.NEVER_EXPIRATION);
             } catch (Exception e2) {
-                System.out.println("Failed to inject cache!");
-                e2.addSuppressed(e);
-                e2.printStackTrace();
-                return;
+                try {
+                    CacheUtil_J8.setInetAddressCache("s.optifine.net", injectedIps, CacheUtilCommons.NEVER_EXPIRATION);
+                } catch (Exception e3) {
+                    System.out.println("Failed to inject cache!");
+                    e2.addSuppressed(e);
+                    e2.printStackTrace();
+                    e3.addSuppressed(e);
+                    e3.printStackTrace();
+                    return;
+                }
             }
         }
         System.out.println("Added DNS cache entry: s.optifine.net/"+args);
diff --git a/arc_dns_injector/src/main/java/git/artdeell/arcdns/CacheUtil_J21.java b/arc_dns_injector/src/main/java/git/artdeell/arcdns/CacheUtil_J21.java
new file mode 100644
index 000000000..8e2501a7a
--- /dev/null
+++ b/arc_dns_injector/src/main/java/git/artdeell/arcdns/CacheUtil_J21.java
@@ -0,0 +1,145 @@
+package git.artdeell.arcdns;
+import static git.artdeell.arcdns.CacheUtilCommons.NEVER_EXPIRATION;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Field;
+import java.lang.reflect.InvocationTargetException;
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.ConcurrentSkipListSet;
+public class CacheUtil_J21 {
+    public static void setInetAddressCache(String host, String[] ips, long expireMillis)
+            throws UnknownHostException, IllegalAccessException, InstantiationException,
+            InvocationTargetException, ClassNotFoundException, NoSuchFieldException {
+        long expiration = expireMillis == NEVER_EXPIRATION ? NEVER_EXPIRATION : System.nanoTime() + expireMillis * 1_000_000;
+        Object cachedAddresses = newCachedAddresses(host, ips, expiration);
+
+        getCacheOfInetAddress().put(host, cachedAddresses);
+        getExpirySetOfInetAddress().add(cachedAddresses);
+    }
+
+    private static Object newCachedAddresses(String host, String[] ips, long expiration)
+            throws ClassNotFoundException, UnknownHostException, IllegalAccessException,
+            InvocationTargetException, InstantiationException {
+        // InetAddress.CachedAddresses has only one constructor
+        return getConstructorOfInetAddress$CachedAddresses().newInstance(host, CacheUtilCommons.toInetAddressArray(host, ips), expiration);
+    }
+
+    private static volatile Constructor<?> constructorOfInetAddress$CachedAddresses = null;
+
+    private static Constructor<?> getConstructorOfInetAddress$CachedAddresses() throws ClassNotFoundException {
+        if (constructorOfInetAddress$CachedAddresses != null) return constructorOfInetAddress$CachedAddresses;
+
+        synchronized (CacheUtilCommons.class) {
+            // double check
+            if (constructorOfInetAddress$CachedAddresses != null) return constructorOfInetAddress$CachedAddresses;
+
+            final Class<?> clazz = Class.forName(inetAddress$CachedAddresses_ClassName);
+
+            // InetAddress.CacheEntry has only one constructor:
+            //
+            // - for jdk 9-jdk12, constructor signature is CachedAddresses(String host, InetAddress[] inetAddresses, long expiryTime)
+            // code in jdk 9:
+            //   https://hg.openjdk.java.net/jdk9/jdk9/jdk/file/65464a307408/src/java.base/share/classes/java/net/InetAddress.java#l783
+            // code in jdk 11:
+            //   https://hg.openjdk.java.net/jdk/jdk11/file/1ddf9a99e4ad/src/java.base/share/classes/java/net/InetAddress.java#l787
+            final Constructor<?> constructor = clazz.getDeclaredConstructors()[0];
+            constructor.setAccessible(true);
+
+            constructorOfInetAddress$CachedAddresses = constructor;
+            return constructor;
+        }
+    }
+
+    public static void removeInetAddressCache(String host) throws NoSuchFieldException, IllegalAccessException {
+        getCacheOfInetAddress().remove(host);
+        removeHostFromExpirySetOfInetAddress(host);
+    }
+
+    /**
+     * @see #getExpirySetOfInetAddress()
+     */
+    private static void removeHostFromExpirySetOfInetAddress(String host)
+            throws NoSuchFieldException, IllegalAccessException {
+        for (Iterator<Object> iterator = getExpirySetOfInetAddress().iterator(); iterator.hasNext(); ) {
+            Object cachedAddresses = iterator.next();
+            if (getHostOfInetAddress$CacheAddress(cachedAddresses).equals(host)) {
+                iterator.remove();
+            }
+        }
+    }
+
+    private static volatile Field hostFieldOfInetAddress$CacheAddress = null;
+
+    private static String getHostOfInetAddress$CacheAddress(Object cachedAddresses)
+            throws NoSuchFieldException, IllegalAccessException {
+        if (hostFieldOfInetAddress$CacheAddress == null) {
+            synchronized (CacheUtil_J21.class) {
+                if (hostFieldOfInetAddress$CacheAddress == null) { // double check
+                    final Field f = cachedAddresses.getClass().getDeclaredField("host");
+                    f.setAccessible(true);
+                    hostFieldOfInetAddress$CacheAddress = f;
+                }
+            }
+        }
+        return (String) hostFieldOfInetAddress$CacheAddress.get(cachedAddresses);
+    }
+
+
+    //////////////////////////////////////////////////////////////////////////////
+    // getters of static cache related fields of InetAddress
+    //////////////////////////////////////////////////////////////////////////////
+
+    @SuppressWarnings("unchecked")
+    private static ConcurrentMap<String, Object> getCacheOfInetAddress()
+            throws NoSuchFieldException, IllegalAccessException {
+        return (ConcurrentMap<String, Object>) getCacheAndExpirySetOfInetAddress0()[0];
+    }
+
+    @SuppressWarnings("unchecked")
+    private static ConcurrentSkipListSet<Object> getExpirySetOfInetAddress()
+            throws NoSuchFieldException, IllegalAccessException {
+        return (ConcurrentSkipListSet<Object>) getCacheAndExpirySetOfInetAddress0()[1];
+    }
+
+    private static volatile Object[] ADDRESS_CACHE_AND_EXPIRY_SET = null;
+
+    private static Object[] getCacheAndExpirySetOfInetAddress0()
+            throws NoSuchFieldException, IllegalAccessException {
+        if (ADDRESS_CACHE_AND_EXPIRY_SET != null) return ADDRESS_CACHE_AND_EXPIRY_SET;
+
+        synchronized (CacheUtil_J21.class) {
+            if (ADDRESS_CACHE_AND_EXPIRY_SET != null) return ADDRESS_CACHE_AND_EXPIRY_SET;
+
+            final Field cacheField = InetAddress.class.getDeclaredField("cache");
+            cacheField.setAccessible(true);
+
+            final Field expirySetField = InetAddress.class.getDeclaredField("expirySet");
+            expirySetField.setAccessible(true);
+
+            ADDRESS_CACHE_AND_EXPIRY_SET = new Object[]{
+                    cacheField.get(InetAddress.class),
+                    expirySetField.get(InetAddress.class)
+            };
+
+            return ADDRESS_CACHE_AND_EXPIRY_SET;
+        }
+    }
+
+    //////////////////////////////////////////////////////////////////////////////
+
+    private static final String inetAddress$CachedAddresses_ClassName = "java.net.InetAddress$CachedLookup";
+    public static void clearInetAddressCache() throws NoSuchFieldException, IllegalAccessException {
+        getCacheOfInetAddress().clear();
+        getExpirySetOfInetAddress().clear();
+    }
+
+    private CacheUtil_J21() {
+    }
+
+}