diff --git a/src/main/java/net/onrc/onos/registry/controller/ControllerRegistryResource.java b/src/main/java/net/onrc/onos/registry/controller/ControllerRegistryResource.java
index 5da2e7c..a68c187 100644
--- a/src/main/java/net/onrc/onos/registry/controller/ControllerRegistryResource.java
+++ b/src/main/java/net/onrc/onos/registry/controller/ControllerRegistryResource.java
@@ -32,7 +32,7 @@
 		if (controllers == null){
 			controllers = new ArrayList<String>();
 			Response response = getResponse();
-			response.setStatus(Status.CLIENT_ERROR_NOT_FOUND);
+			response.setStatus(Status.CLIENT_ERROR_UNPROCESSABLE_ENTITY);
 			Representation error = new StringRepresentation("Null data returned. Zookeeper connection may be down");
 			response.setEntity(error);
 			return null;
diff --git a/src/main/java/net/onrc/onos/registry/controller/ZookeeperRegistry.java b/src/main/java/net/onrc/onos/registry/controller/ZookeeperRegistry.java
index 58b66f2..eb2afb3 100644
--- a/src/main/java/net/onrc/onos/registry/controller/ZookeeperRegistry.java
+++ b/src/main/java/net/onrc/onos/registry/controller/ZookeeperRegistry.java
@@ -36,6 +36,8 @@
 import com.netflix.curator.framework.recipes.leader.LeaderLatchEvent;
 import com.netflix.curator.framework.recipes.leader.LeaderLatchListener;
 import com.netflix.curator.framework.recipes.leader.Participant;
+import com.netflix.curator.framework.state.ConnectionState;
+import com.netflix.curator.framework.state.ConnectionStateListener;
 import com.netflix.curator.retry.ExponentialBackoffRetry;
 import com.netflix.curator.utils.ZKPaths;
 
@@ -71,6 +73,17 @@
 	protected static final int sessionTimeout = 5000;
 	protected static final int connectionTimeout = 7000;
 	
+	//We can cache the connection state here whenever we get a connection state event.
+	//Not 100% accurate but it's good enough to decide whether we can return data
+	//via the REST API or not.
+	protected volatile ConnectionState connectionState = ConnectionState.LOST;
+	
+	protected ConnectionStateListener connectionStateListener = new ConnectionStateListener(){
+		@Override
+		public void stateChanged(CuratorFramework client, ConnectionState state) {
+			connectionState = state;
+		}
+	};
 
 	protected class SwitchLeaderListener implements LeaderLatchListener{
 		String dpid;
@@ -239,9 +252,16 @@
 		
 		//Rebuild the cache to make sure we have the latest data
 		//If we don't have ZK connection this will hang until we do. Undesirable.
-		try {
-			controllerCache.rebuild();
-		} catch (Exception e1) {
+		//try {
+			//controllerCache.rebuild();
+		//} catch (Exception e1) {
+			//return null;
+		//}
+		ConnectionState currentConnectionState = connectionState;
+		//if (currentConnectionState != ConnectionState.CONNECTED && 
+			//	currentConnectionState != ConnectionState.RECONNECTED){
+		if (currentConnectionState == ConnectionState.LOST ||
+				currentConnectionState == ConnectionState.SUSPENDED){
 			return null;
 		}
 		
@@ -435,7 +455,7 @@
 		RetryPolicy retryPolicy = new ExponentialBackoffRetry(1000, 3);
 		client = CuratorFrameworkFactory.newClient(this.connectionString, 
 				sessionTimeout, connectionTimeout, retryPolicy);
-		
+		client.getConnectionStateListenable().addListener(connectionStateListener);
 		client.start();
 		client = client.usingNamespace(namespace);