diff --git a/pkg/apis/config/defaults.go b/pkg/apis/config/defaults.go
index f12b83ab534..9f68edf86f8 100644
--- a/pkg/apis/config/defaults.go
+++ b/pkg/apis/config/defaults.go
@@ -71,20 +71,33 @@ func NewDefaultsConfigFromConfigMap(config *corev1.ConfigMap) (*Defaults, error)
 // Defaults includes the default values to be populated by the webhook.
 type Defaults struct {
 	// NamespaceDefaultsConfig are the default Broker Configs for each namespace.
-	// Namespace is the key, the value is the KReference to the config.
-	NamespaceDefaultsConfig map[string]*ClassAndBrokerConfig `json:"namespaceDefaults,omitempty"`
+	// Namespace is the key, the value is the NamespaceDefaultConfig
+	NamespaceDefaultsConfig *NamespaceDefaultsConfig `json:"namespaceDefaults,omitempty"`
 
-	// ClusterDefaultBrokerConfig is the default broker config for all the namespaces that
-	// are not in NamespaceDefaultBrokerConfigs.
-	ClusterDefault *ClassAndBrokerConfig `json:"clusterDefault,omitempty"`
+	// ClusterDefaultConfig is the default broker config for all the namespaces that
+	// are not in NamespaceDefaultBrokerConfigs. Different broker class could have
+	// different default config.
+	ClusterDefaultConfig *DefaultConfig `json:"clusterDefault,omitempty"`
 }
 
-// ClassAndBrokerConfig contains configuration for a given namespace for broker. Allows
-// configuring the Class of the Broker, the reference to the
-// config it should use and it's delivery.
-type ClassAndBrokerConfig struct {
-	BrokerClass   string `json:"brokerClass,omitempty"`
-	*BrokerConfig `json:",inline"`
+// DefaultConfig struct contains the default configuration for the cluster and namespace.
+type DefaultConfig struct {
+	// DefaultBrokerClass and DefaultBrokerClassConfig are the default broker class for the whole cluster
+	// Users have to specify both of them
+	DefaultBrokerClass       string        `json:"brokerClass,omitempty"`
+	DefaultBrokerClassConfig *BrokerConfig `json:",inline"`
+
+	// BrokerClasses are the default broker classes' config for the whole cluster
+	BrokerClasses map[string]*BrokerConfig `json:"brokerClasses,omitempty"`
+
+	DisallowDifferentNamespaceConfig *bool `json:"disallowDifferentNamespaceConfig,omitempty"`
+}
+
+// NamespaceDefaultsConfig struct contains the default configuration for the namespace.
+type NamespaceDefaultsConfig struct {
+
+	// BrokerClasses are the default broker classes' config for the namespace
+	NameSpaces map[string]*DefaultConfig `json:"brokerClasses,omitempty"`
 
 	DisallowDifferentNamespaceConfig *bool `json:"disallowDifferentNamespaceConfig,omitempty"`
 }
@@ -100,33 +113,94 @@ type BrokerConfig struct {
 // GetBrokerConfig returns a namespace specific Broker Configuration, and if
 // that doesn't exist, return a Cluster Default and if that doesn't exist
 // return an error.
-func (d *Defaults) GetBrokerConfig(ns string) (*BrokerConfig, error) {
+func (d *Defaults) GetBrokerConfig(ns string, brokerClassName string) (*BrokerConfig, error) {
+
 	if d == nil {
 		return nil, errors.New("Defaults are nil")
 	}
-	value, present := d.NamespaceDefaultsConfig[ns]
-	if present && value.BrokerConfig != nil {
-		return value.BrokerConfig, nil
+
+	value, present := d.NamespaceDefaultsConfig.NameSpaces[ns]
+	if present && value != nil {
+		// We have the namespace specific config
+		// Now check whether the brokerClassName is the default broker class for this namespace
+		if value.DefaultBrokerClass == brokerClassName {
+			// return the default broker class config for this namespace
+			return value.DefaultBrokerClassConfig, nil
+		} else {
+			// If the brokerClassName is not the default broker class for this namespace, check if we have the config for this brokerclass
+			if value.BrokerClasses != nil {
+				brokerConfig, present := value.BrokerClasses[brokerClassName]
+				if present && brokerConfig != nil {
+					// We have the config specifically for this broker class in this namespace, just return the config
+					return brokerConfig, nil
+				} else {
+					// We don't have the config specifically for this broker class in this namespace, check the default broker class config for this namespace
+					if value.DefaultBrokerClassConfig != nil {
+						// return the default broker class config for this namespace
+						return value.DefaultBrokerClassConfig, nil
+					} else {
+						// We don't have the default broker class config for this namespace, check if we have the cluster default config
+						if d.ClusterDefaultConfig != nil && d.ClusterDefaultConfig.DefaultBrokerClassConfig != nil {
+							return d.ClusterDefaultConfig.DefaultBrokerClassConfig, nil
+						} else {
+							return nil, errors.New("Defaults for Broker Configurations have not been set up.")
+						}
+					}
+				}
+
+			} else {
+				// No brokerClasses config for this namespace, check the default broker class config for this namespace
+				if value.DefaultBrokerClassConfig != nil {
+					// return the default broker class config for this namespace
+					return value.DefaultBrokerClassConfig, nil
+				} else {
+					// We don't have the default broker class config for this namespace, check if we have the cluster default config
+					if d.ClusterDefaultConfig != nil && d.ClusterDefaultConfig.DefaultBrokerClassConfig != nil {
+						return d.ClusterDefaultConfig.DefaultBrokerClassConfig, nil
+					} else {
+						return nil, errors.New("Defaults for Broker Configurations have not been set up. Both default broker class config for this namespace and cluster default config are nil.")
+					}
+				}
+			}
+		}
 	}
-	if d.ClusterDefault != nil && d.ClusterDefault.BrokerConfig != nil {
-		return d.ClusterDefault.BrokerConfig, nil
+	if d.ClusterDefaultConfig != nil && d.ClusterDefaultConfig.DefaultBrokerClassConfig != nil {
+		return d.ClusterDefaultConfig.DefaultBrokerClassConfig, nil
 	}
 	return nil, errors.New("Defaults for Broker Configurations have not been set up.")
+
 }
 
 // GetBrokerClass returns a namespace specific Broker Class, and if
 // that doesn't exist, return a Cluster Default and if that doesn't exist
 // return an error.
 func (d *Defaults) GetBrokerClass(ns string) (string, error) {
+
 	if d == nil {
 		return "", errors.New("Defaults are nil")
 	}
-	value, present := d.NamespaceDefaultsConfig[ns]
-	if present && value.BrokerClass != "" {
-		return value.BrokerClass, nil
-	}
-	if d.ClusterDefault != nil && d.ClusterDefault.BrokerClass != "" {
-		return d.ClusterDefault.BrokerClass, nil
+
+	value, present := d.NamespaceDefaultsConfig.NameSpaces[ns]
+	if present && value != nil {
+		// We have the namespace specific config
+		// Now check whether the brokerClassName is the default broker class for this namespace
+		if value.DefaultBrokerClass != "" {
+			// return the default broker class for this namespace
+			return value.DefaultBrokerClass, nil
+		} else {
+			// If the brokerClassName is not set for this namespace, we will check for the cluster default config
+			if d.ClusterDefaultConfig != nil && d.ClusterDefaultConfig.DefaultBrokerClass != "" {
+				return d.ClusterDefaultConfig.DefaultBrokerClass, nil
+			} else {
+				return "", errors.New("Defaults for Broker Configurations have not been set up.")
+			}
+		}
+	} else {
+		// We don't have the namespace specific config, check for the cluster default config
+		if d.ClusterDefaultConfig != nil && d.ClusterDefaultConfig.DefaultBrokerClass != "" {
+			return d.ClusterDefaultConfig.DefaultBrokerClass, nil
+		} else {
+			return "", errors.New("Defaults for Broker Configurations have not been set up.")
+		}
 	}
-	return "", errors.New("Defaults for Broker Configurations have not been set up.")
 }