Index: java/org/apache/catalina/Realm.java
===================================================================
--- java/org/apache/catalina/Realm.java	(revision 1765945)
+++ java/org/apache/catalina/Realm.java	(working copy)
@@ -231,4 +231,13 @@
      * @return principal roles
      */
     public String[] getRoles(Principal principal);
+
+
+    /**
+     * Return the availability of the realm for authentication.
+     * @return <code>true</code> if the realm is able to perform authentication
+     */
+    default public boolean isAvailable() {
+        return true;
+    }
 }
Index: java/org/apache/catalina/realm/CombinedRealm.java
===================================================================
--- java/org/apache/catalina/realm/CombinedRealm.java	(revision 1765945)
+++ java/org/apache/catalina/realm/CombinedRealm.java	(working copy)
@@ -418,4 +418,15 @@
         throw uoe;
     }
 
+
+    @Override
+    public boolean isAvailable() {
+        for (Realm realm : realms) {
+            if (!realm.isAvailable()) {
+                return false;
+            }
+        }
+        return true;
+    }
+
 }
Index: java/org/apache/catalina/realm/JNDIRealm.java
===================================================================
--- java/org/apache/catalina/realm/JNDIRealm.java	(revision 1765945)
+++ java/org/apache/catalina/realm/JNDIRealm.java	(working copy)
@@ -2379,6 +2379,12 @@
 
     }
 
+    @Override
+    public boolean isAvailable() {
+        // Simple best effort check
+        return (context != null);
+    }
+
     private DirContext createDirContext(Hashtable<String, String> env) throws NamingException {
         if (useStartTls) {
             return createTlsDirContext(env);
Index: java/org/apache/catalina/realm/DataSourceRealm.java
===================================================================
--- java/org/apache/catalina/realm/DataSourceRealm.java	(revision 1765945)
+++ java/org/apache/catalina/realm/DataSourceRealm.java	(working copy)
@@ -107,6 +107,12 @@
     protected String userTable = null;
 
 
+    /**
+     * Last connection attempt.
+     */
+    private volatile boolean connectionSuccess = true;
+
+
     // ------------------------------------------------------------- Properties
 
 
@@ -270,6 +276,11 @@
     }
 
 
+    @Override
+    public boolean isAvailable() {
+        return connectionSuccess;
+    }
+
     // -------------------------------------------------------- Package Methods
 
 
@@ -378,8 +389,11 @@
                 context = getServer().getGlobalNamingContext();
             }
             DataSource dataSource = (DataSource)context.lookup(dataSourceName);
-        return dataSource.getConnection();
+            Connection connection = dataSource.getConnection();
+            connectionSuccess = true;
+            return connection;
         } catch (Exception e) {
+            connectionSuccess = false; 
             // Log the problem for posterity
             containerLog.error(sm.getString("dataSourceRealm.exception"), e);
         }
Index: java/org/apache/catalina/realm/LockOutRealm.java
===================================================================
--- java/org/apache/catalina/realm/LockOutRealm.java	(revision 1765945)
+++ java/org/apache/catalina/realm/LockOutRealm.java	(working copy)
@@ -212,7 +212,7 @@
      */
     private Principal filterLockedAccounts(String username, Principal authenticatedUser) {
         // Register all failed authentications
-        if (authenticatedUser == null) {
+        if (authenticatedUser == null && isAvailable()) {
             registerAuthFailure(username);
         }
 
Index: java/org/apache/catalina/realm/JDBCRealm.java
===================================================================
--- java/org/apache/catalina/realm/JDBCRealm.java	(revision 1765945)
+++ java/org/apache/catalina/realm/JDBCRealm.java	(working copy)
@@ -414,6 +414,12 @@
     }
 
 
+    @Override
+    public boolean isAvailable() {
+        return (dbConnection != null);
+    }
+
+
     /**
      * Close the specified database connection.
      *