diff --git a/src/main/java/de/rpr/ddnsclient/AppConfig.java b/src/main/java/de/rpr/ddnsclient/AppConfig.java
index 8d905b9..0fd4877 100644
--- a/src/main/java/de/rpr/ddnsclient/AppConfig.java
+++ b/src/main/java/de/rpr/ddnsclient/AppConfig.java
@@ -4,9 +4,16 @@ import com.fasterxml.jackson.databind.ObjectMapper;
 import de.rpr.ddnsclient.model.Config;
 import jakarta.enterprise.context.ApplicationScoped;
 import jakarta.ws.rs.Produces;
+import org.eclipse.microprofile.config.inject.ConfigProperty;
 
+import javax.naming.Context;
+import javax.naming.NamingException;
+import javax.naming.directory.DirContext;
+import javax.naming.directory.InitialDirContext;
 import java.io.File;
 import java.io.IOException;
+import java.text.MessageFormat;
+import java.util.Properties;
 
 public class AppConfig {
 
@@ -17,4 +24,14 @@ public class AppConfig {
         return objectMapper.readValue(configFile, Config.class);
     }
 
+    @Produces
+    @ApplicationScoped
+    public DirContext dirContext(
+            @ConfigProperty(name = "ddnsclient.dns.resolver", defaultValue = "9.9.9.9") String dnsServer)
+            throws NamingException {
+        Properties env = new Properties();
+        env.setProperty(Context.INITIAL_CONTEXT_FACTORY, "com.sun.jndi.dns.DnsContextFactory");
+        env.setProperty(Context.PROVIDER_URL, MessageFormat.format("dns://{0}", dnsServer));
+        return new InitialDirContext(env);
+    }
 }
diff --git a/src/main/java/de/rpr/ddnsclient/lookup/DnsResolver.java b/src/main/java/de/rpr/ddnsclient/lookup/DnsResolver.java
index 5cfb2db..29da784 100644
--- a/src/main/java/de/rpr/ddnsclient/lookup/DnsResolver.java
+++ b/src/main/java/de/rpr/ddnsclient/lookup/DnsResolver.java
@@ -1,19 +1,13 @@
 package de.rpr.ddnsclient.lookup;
 
 
-import de.rpr.ddnsclient.dyndns.Ddnss;
 import de.rpr.ddnsclient.model.IPs;
 import jakarta.enterprise.context.ApplicationScoped;
-import org.eclipse.microprofile.config.inject.ConfigProperty;
 import org.jboss.logging.Logger;
 
-import javax.naming.Context;
 import javax.naming.NamingException;
 import javax.naming.directory.Attributes;
 import javax.naming.directory.DirContext;
-import javax.naming.directory.InitialDirContext;
-import java.text.MessageFormat;
-import java.util.Properties;
 
 @ApplicationScoped
 public class DnsResolver {
@@ -21,11 +15,10 @@ public class DnsResolver {
     private static final Logger log = Logger.getLogger(DnsResolver.class);
 
     public static final int MAX_RETRIES = 5;
-    private final Properties env = new Properties();
+    private final DirContext dirContext;
 
-    public DnsResolver(@ConfigProperty(name = "ddnsclient.dns.resolver", defaultValue = "9.9.9.9") String dnsServer) {
-        env.setProperty(Context.INITIAL_CONTEXT_FACTORY, "com.sun.jndi.dns.DnsContextFactory");
-        env.setProperty(Context.PROVIDER_URL, MessageFormat.format("dns://{0}", dnsServer));
+    DnsResolver(DirContext dirContext) {
+        this.dirContext = dirContext;
     }
 
     public IPs resolve(String hostname) {
@@ -34,16 +27,15 @@ public class DnsResolver {
 
         int resolveCounter = 0;
         try {
-            DirContext context = new InitialDirContext((env));
 
             Attributes result;
             do {
                 if (resolveCounter == MAX_RETRIES) {
-                    throw new RuntimeException("Couldn't resolve " + hostname);
+                    throw new IllegalStateException("Couldn't resolve all attributes");
                 }
                 resolveCounter++;
                 log.tracef("Try #%d", resolveCounter);
-                result = context.getAttributes(hostname, new String[]{"A", "AAAA"});
+                result = dirContext.getAttributes(hostname, new String[]{"A", "AAAA"});
             } while (result.size() != 2);
 
             return new IPs(
diff --git a/src/test/java/de/rpr/ddnsclient/lookup/DnsResolverTest.java b/src/test/java/de/rpr/ddnsclient/lookup/DnsResolverTest.java
new file mode 100644
index 0000000..5d5e5d3
--- /dev/null
+++ b/src/test/java/de/rpr/ddnsclient/lookup/DnsResolverTest.java
@@ -0,0 +1,53 @@
+package de.rpr.ddnsclient.lookup;
+
+import de.rpr.ddnsclient.model.IPs;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+import javax.naming.NamingException;
+import javax.naming.directory.BasicAttributes;
+import javax.naming.directory.DirContext;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.AssertionsForClassTypes.assertThatExceptionOfType;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.Mockito.when;
+
+@ExtendWith(MockitoExtension.class)
+class DnsResolverTest {
+
+    @Mock
+    DirContext dirContext;
+
+    @Test
+    void should_throw_exception_if_resolving_failes_repeatedly() throws NamingException {
+
+        when(dirContext.getAttributes(anyString(), any())).thenReturn(new BasicAttributes());
+
+        DnsResolver dnsResolver = new DnsResolver(dirContext);
+
+        assertThatExceptionOfType(IllegalStateException.class)
+                .isThrownBy(() -> dnsResolver.resolve("example.com"));
+    }
+
+    @Test
+    void should_return_ips() throws NamingException {
+
+        BasicAttributes attributes = new BasicAttributes() {{
+            put("A", "ipv4");
+            put("AAAA", "ipv6");
+        }};
+        when(dirContext.getAttributes(anyString(), any())).thenReturn(attributes);
+
+        DnsResolver dnsResolver = new DnsResolver(dirContext);
+
+        IPs result = dnsResolver.resolve("example.com");
+
+        assertThat(result.v4()).isEqualTo("ipv4");
+        assertThat(result.v6()).isEqualTo("ipv6");
+
+    }
+}
\ No newline at end of file