diff --git a/core-java-modules/core-java-18/src/main/java/com/baeldung/inetspi/InetAddressSPI.java b/core-java-modules/core-java-18/src/main/java/com/baeldung/inetspi/InetAddressSPI.java
new file mode 100644
index 0000000000..0d5f5c486a
--- /dev/null
+++ b/core-java-modules/core-java-18/src/main/java/com/baeldung/inetspi/InetAddressSPI.java
@@ -0,0 +1,44 @@
+package com.baeldung.inetspi;
+
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+import java.util.Arrays;
+import java.util.stream.Stream;
+
+import com.baeldung.inetspi.providers.CustomAddressResolverImpl;
+
+public class InetAddressSPI {
+    public String usingGetByName(String host) throws UnknownHostException {
+        InetAddress inetAddress =  InetAddress.getByName(host);
+        return inetAddress.getHostAddress();
+    }
+
+    public String[] usingGetAllByName(String host) throws UnknownHostException {
+        InetAddress[] inetAddresses =  InetAddress.getAllByName(host);
+        return Arrays.stream(inetAddresses).map(InetAddress::getHostAddress).toArray(String[]::new);
+    }
+
+    public String usingGetByIp(byte[] ip) throws UnknownHostException {
+        InetAddress inetAddress =  InetAddress.getByAddress(ip);
+
+        return inetAddress.getHostName();
+    }
+
+    public String usingGetByIpAndReturnsCannonName(byte[] ip) throws UnknownHostException {
+        InetAddress inetAddress =  InetAddress.getByAddress(ip);
+
+        return inetAddress.getCanonicalHostName();
+    }
+
+    public String getHostUsingCustomImpl(byte[] ip) throws UnknownHostException {
+
+        CustomAddressResolverImpl imp = new CustomAddressResolverImpl();
+        return imp.get(null).lookupByAddress(ip);
+    }
+
+    public Stream<InetAddress> getIpUsingCustomImpl(String host) throws UnknownHostException {
+
+        CustomAddressResolverImpl imp = new CustomAddressResolverImpl();
+        return imp.get(null).lookupByName(host, null);
+    }
+}
diff --git a/core-java-modules/core-java-18/src/main/java/com/baeldung/inetspi/Registry.java b/core-java-modules/core-java-18/src/main/java/com/baeldung/inetspi/Registry.java
new file mode 100644
index 0000000000..db15f6a8d4
--- /dev/null
+++ b/core-java-modules/core-java-18/src/main/java/com/baeldung/inetspi/Registry.java
@@ -0,0 +1,56 @@
+package com.baeldung.inetspi;
+
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.logging.Logger;
+import java.util.stream.Stream;
+
+public class Registry {
+    private final Map<String, List<byte[]>> registry;
+
+    private static final Logger LOGGER = Logger.getLogger(Registry.class.getName());
+
+    public Registry() {
+        registry = loadMapWithData();
+    }
+
+    public Stream<InetAddress> getAddressesfromHost(String host) throws UnknownHostException {
+        LOGGER.info("Performing Forward Lookup for HOST : " + host);
+        if (!registry.containsKey(host)) {
+            throw new UnknownHostException("Missing Host information in Resolver");
+        }
+        return registry.get(host)
+          .stream()
+          .map(add -> constructInetAddress(host, add))
+          .filter(Objects::nonNull);
+    }
+
+    public String getHostFromAddress(byte[] arr) throws UnknownHostException {
+        LOGGER.info("Performing Reverse Lookup for Address : " + Arrays.toString(arr));
+        for (Map.Entry<String, List<byte[]>> entry : registry.entrySet()) {
+            if (entry.getValue()
+              .stream()
+              .anyMatch(ba -> Arrays.equals(ba, arr))) {
+                return entry.getKey();
+            }
+        }
+        throw new UnknownHostException("Address Not Found");
+    }
+
+    private Map<String, List<byte[]>> loadMapWithData() {
+        return Map.of("baeldung-local.org", List.of(new byte[] { 1, 2, 3, 4 }));
+    }
+
+    private static InetAddress constructInetAddress(String host, byte[] address) {
+        try {
+            return InetAddress.getByAddress(host, address);
+        } catch (UnknownHostException unknownHostException) {
+            return null;
+        }
+    }
+
+}
diff --git a/core-java-modules/core-java-18/src/main/java/com/baeldung/inetspi/providers/CustomAddressResolverImpl.java b/core-java-modules/core-java-18/src/main/java/com/baeldung/inetspi/providers/CustomAddressResolverImpl.java
new file mode 100644
index 0000000000..0b1849c3f9
--- /dev/null
+++ b/core-java-modules/core-java-18/src/main/java/com/baeldung/inetspi/providers/CustomAddressResolverImpl.java
@@ -0,0 +1,42 @@
+package com.baeldung.inetspi.providers;
+
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+import java.net.spi.InetAddressResolver;
+import java.net.spi.InetAddressResolverProvider;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.logging.Logger;
+import java.util.stream.Stream;
+
+import com.baeldung.inetspi.Registry;
+
+public class CustomAddressResolverImpl extends InetAddressResolverProvider {
+
+    private static Logger LOGGER = Logger.getLogger(CustomAddressResolverImpl.class.getName());
+
+    private static Registry registry = new Registry();
+
+    @Override
+    public InetAddressResolver get(Configuration configuration) {
+        LOGGER.info("Using Custom Address Resolver :: " + this.name());
+        LOGGER.info("Registry initialised");
+        return new InetAddressResolver() {
+            @Override
+            public Stream<InetAddress> lookupByName(String host, LookupPolicy lookupPolicy) throws UnknownHostException {
+                return registry.getAddressesfromHost(host);
+            }
+
+            @Override
+            public String lookupByAddress(byte[] addr) throws UnknownHostException {
+                return registry.getHostFromAddress(addr);
+            }
+        };
+    }
+
+    @Override
+    public String name() {
+        return "CustomInternetAddressResolverImpl";
+    }
+}
diff --git a/core-java-modules/core-java-18/src/test/java/com/baeldung/inetspi/InetAddressSPIUnitTest.java b/core-java-modules/core-java-18/src/test/java/com/baeldung/inetspi/InetAddressSPIUnitTest.java
new file mode 100644
index 0000000000..ad8e6f0e54
--- /dev/null
+++ b/core-java-modules/core-java-18/src/test/java/com/baeldung/inetspi/InetAddressSPIUnitTest.java
@@ -0,0 +1,31 @@
+package com.baeldung.inetspi;
+
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+import java.util.stream.Stream;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class InetAddressSPIUnitTest {
+    @Test
+    public void givenInetAddress_whenUsingInetAddress_thenPerformResolution() throws UnknownHostException {
+        InetAddressSPI spi = new InetAddressSPI();
+        Assert.assertNotNull(spi.usingGetByName("www.google.com"));
+        Assert.assertTrue(spi.usingGetAllByName("www.google.com").length > 1);
+        Assert.assertNotNull(spi.usingGetByIp(InetAddress.getByName("www.google.com")
+          .getAddress()));
+        Assert.assertNotNull(spi.usingGetByIpAndReturnsCannonName(InetAddress.getByName("www.google.com")
+          .getAddress()));
+    }
+
+    @Test
+    public void givenCustomInetAddressImplementation_whenUsingInetAddress_thenPerformResolution() throws UnknownHostException {
+        InetAddressSPI spi = new InetAddressSPI();
+        Assert.assertEquals("baeldung-local.org", spi.getHostUsingCustomImpl(new byte[] { 1, 2, 3, 4 }));
+        Stream<InetAddress> response = spi.getIpUsingCustomImpl("baeldung-local.org");
+        Assert.assertArrayEquals(new byte[] { 1, 2, 3, 4 }, response.findFirst()
+          .get()
+          .getAddress());
+    }
+}