diff --git a/client.go b/client.go
index c2b8ecb6..5f2d6e5a 100644
--- a/client.go
+++ b/client.go
@@ -20,6 +20,7 @@ package agollo
 import (
 	"container/list"
 	"errors"
+	"strings"
 
 	"github.com/apolloconfig/agollo/v4/agcache"
 	"github.com/apolloconfig/agollo/v4/agcache/memory"
@@ -158,19 +159,40 @@ func (c *internalClient) GetConfigAndInit(namespace string) *storage.Config {
 		return nil
 	}
 
-	config := c.cache.GetConfig(namespace)
+	cfg := c.cache.GetConfig(namespace)
 
-	if config == nil {
+	if cfg == nil {
 		//sync config
 		apolloConfig := syncApolloConfig.SyncWithNamespace(namespace, c.getAppConfig)
 		if apolloConfig != nil {
-			c.cache.UpdateApolloConfig(apolloConfig, c.getAppConfig)
+			c.SyncAndUpdate(namespace, apolloConfig)
+		}
+	}
+
+	cfg = c.cache.GetConfig(namespace)
+
+	return cfg
+}
+
+func (c *internalClient) SyncAndUpdate(namespace string, apolloConfig *config.ApolloConfig) {
+	// update appConfig only if namespace does not exist yet
+	namespaces := strings.Split(c.appConfig.NamespaceName, ",")
+	exists := false
+	for _, n := range namespaces {
+		if n == namespace {
+			exists = true
+			break
 		}
 	}
+	if !exists {
+		c.appConfig.NamespaceName += "," + namespace
+	}
 
-	config = c.cache.GetConfig(namespace)
+	// update notification
+	c.appConfig.GetNotificationsMap().UpdateNotify(namespace, 0)
 
-	return config
+	// update cache
+	c.cache.UpdateApolloConfig(apolloConfig, c.getAppConfig)
 }
 
 // GetConfigCache 根据namespace获取apollo配置的缓存
diff --git a/client_test.go b/client_test.go
index 41ffc31d..8a2d7d00 100644
--- a/client_test.go
+++ b/client_test.go
@@ -365,17 +365,40 @@ func TestGetConfigAndInitValNotNil(t *testing.T) {
 				AppID:         "testID",
 				NamespaceName: "testNotFound",
 			},
-			Configurations: map[string]interface{}{"testKey": "testValue"},
+			Configurations: map[string]interface{}{"testKey": "testUpdatedValue"},
 		}
 	})
-	defer patch.Reset()
 
 	client := createMockApolloConfig(120)
 	cf := client.GetConfig("testNotFound")
 	Assert(t, cf, NotNilVal())
-	// cache should be updated
+
+	// appConfig notificationsMap appConfig should be updated
+	Assert(t, client.appConfig.GetNotificationsMap().GetNotify("testNotFound"), Equal(int64(0)))
+
+	// cache should be updated with new configuration
 	Assert(t, client.cache.GetConfig("testNotFound"), NotNilVal())
-	Assert(t, client.cache.GetConfig("testNotFound").GetValue("testKey"), Equal("testValue"))
+	Assert(t, client.cache.GetConfig("testNotFound").GetValue("testKey"), Equal("testUpdatedValue"))
+	Assert(t, client.appConfig.NamespaceName, Equal("application,testNotFound"))
+	patch.Reset()
+
+	// second replace
+	patch1 := gomonkey.ApplyMethod(reflect.TypeOf(apc), "SyncWithNamespace", func(_ *remote.AbsApolloConfig, namespace string, appConfigFunc func() config.AppConfig) *config.ApolloConfig {
+		return &config.ApolloConfig{
+			ApolloConnConfig: config.ApolloConnConfig{
+				AppID:         "testID",
+				NamespaceName: "testNotFound1",
+			},
+			Configurations: map[string]interface{}{"testKey": "testUpdatedValue"},
+		}
+	})
+	defer patch1.Reset()
+	client.appConfig.NamespaceName = "testNotFound1"
+	cf1 := client.GetConfig("testNotFound1")
+	Assert(t, cf1, NotNilVal())
+	Assert(t, client.cache.GetConfig("testNotFound1"), NotNilVal())
+	// appConfig namespace existed, should not be appended
+	Assert(t, client.appConfig.NamespaceName, Equal("testNotFound1"))
 }
 
 func TestGetConfigAndInitValNil(t *testing.T) {
diff --git a/component/notify/componet_notify_test.go b/component/notify/componet_notify_test.go
index ec3b04a6..bb5c4efc 100644
--- a/component/notify/componet_notify_test.go
+++ b/component/notify/componet_notify_test.go
@@ -102,3 +102,21 @@ func getTestAppConfig() *config.AppConfig {
 	appConfig.Init()
 	return appConfig
 }
+
+func TestConfigComponent_SetAppConfig_UpdatesAppConfigCorrectly(t *testing.T) {
+	expectedAppConfig := getTestAppConfig()
+	c := &ConfigComponent{}
+	// set appConfigFunc
+	c.SetAppConfig(func() config.AppConfig {
+		return *expectedAppConfig
+	})
+
+	// appConfig should be equal
+	Assert(t, c.appConfigFunc(), Equal(*expectedAppConfig))
+
+	// appConfig value is be replaced
+	expectedAppConfig.AppID = "test1"
+	expectedAppConfig.NamespaceName = expectedAppConfig.NamespaceName + config.Comma + "abc"
+	Assert(t, c.appConfigFunc().AppID, Equal("test1"))
+	Assert(t, c.appConfigFunc().NamespaceName, Equal("application,abc"))
+}
diff --git a/component/remote/abs.go b/component/remote/abs.go
index 801a4177..1952a809 100644
--- a/component/remote/abs.go
+++ b/component/remote/abs.go
@@ -18,7 +18,6 @@
 package remote
 
 import (
-	"strconv"
 	"time"
 
 	"github.com/apolloconfig/agollo/v4/component/log"
@@ -47,12 +46,7 @@ func (a *AbsApolloConfig) SyncWithNamespace(namespace string, appConfigFunc func
 		IsRetry: true,
 	}
 	if appConfig.SyncServerTimeout > 0 {
-		duration, err := time.ParseDuration(strconv.Itoa(appConfig.SyncServerTimeout) + "s")
-		if err != nil {
-			log.Errorf("parse sync server timeout %s fail, error:%v", appConfig.SyncServerTimeout, err)
-			return nil
-		}
-		c.Timeout = duration
+		c.Timeout = time.Duration(appConfig.SyncServerTimeout) * time.Second
 	}
 
 	callback := a.remoteApollo.CallBack(namespace)
diff --git a/component/remote/async_test.go b/component/remote/async_test.go
index dcb428e4..c7d645a9 100644
--- a/component/remote/async_test.go
+++ b/component/remote/async_test.go
@@ -146,7 +146,7 @@ func initMockNotifyAndConfigServerWithTwoErrResponse() *httptest.Server {
 	return runMockConfigServer(handlerMap, onlynormaltworesponse)
 }
 
-//run mock config server
+// run mock config server
 func runMockConfigServer(handlerMap map[string]func(http.ResponseWriter, *http.Request),
 	notifyHandler func(http.ResponseWriter, *http.Request)) *httptest.Server {
 	appConfig := env.InitFileConfig()
@@ -177,11 +177,11 @@ func initNotifications() *config.AppConfig {
 	return appConfig
 }
 
-//Error response
-//will hold 5s and keep response 404
-func runErrorResponse() *httptest.Server {
+// Error response with status and body
+func runErrorResponse(status int, body []byte) *httptest.Server {
 	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		w.WriteHeader(http.StatusNotFound)
+		w.WriteHeader(status)
+		_, _ = w.Write(body)
 	}))
 
 	return ts
@@ -281,10 +281,26 @@ func TestGetRemoteConfig(t *testing.T) {
 }
 
 func TestErrorGetRemoteConfig(t *testing.T) {
+	tests := []struct {
+		name         string
+		status       int
+		errContained string
+	}{
+		{name: "500", status: http.StatusInternalServerError, errContained: "over Max Retry Still Error"},
+		{name: "404", status: http.StatusNotFound, errContained: "Connect Apollo Server Fail"},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			testErrorGetRemoteConfig(t, tt.status, tt.errContained)
+		})
+	}
+}
+
+func testErrorGetRemoteConfig(t *testing.T, status int, errContained string) {
 	//clear
 	initNotifications()
 	appConfig := initNotifications()
-	server1 := runErrorResponse()
+	server1 := runErrorResponse(status, nil)
 	appConfig.IP = server1.URL
 	server.SetNextTryConnTime(appConfig.GetHost(), 0)
 
@@ -303,7 +319,7 @@ func TestErrorGetRemoteConfig(t *testing.T) {
 	t.Log("remoteConfigs:", remoteConfigs)
 	t.Log("remoteConfigs size:", len(remoteConfigs))
 
-	Assert(t, "over Max Retry Still Error", Equal(err.Error()))
+	Assert(t, err.Error(), StartWith(errContained))
 }
 
 func TestCreateApolloConfigWithJson(t *testing.T) {
diff --git a/component/serverlist/sync.go b/component/serverlist/sync.go
index 9bb0c402..a554239c 100644
--- a/component/serverlist/sync.go
+++ b/component/serverlist/sync.go
@@ -19,7 +19,6 @@ package serverlist
 
 import (
 	"encoding/json"
-	"strconv"
 	"time"
 
 	"github.com/apolloconfig/agollo/v4/env/server"
@@ -66,10 +65,10 @@ func (s *SyncServerIPListComponent) Start() {
 	}
 }
 
-//SyncServerIPList sync ip list from server
-//then
-//1.update agcache
-//2.store in disk
+// SyncServerIPList sync ip list from server
+// then
+// 1.update agcache
+// 2.store in disk
 func SyncServerIPList(appConfigFunc func() config.AppConfig) (map[string]*config.ServerInfo, error) {
 	if appConfigFunc == nil {
 		panic("can not find apollo config!please confirm!")
@@ -80,12 +79,8 @@ func SyncServerIPList(appConfigFunc func() config.AppConfig) (map[string]*config
 		AppID:  appConfig.AppID,
 		Secret: appConfig.Secret,
 	}
-	if appConfigFunc().SyncServerTimeout > 0 {
-		duration, err := time.ParseDuration(strconv.Itoa(appConfigFunc().SyncServerTimeout) + "s")
-		if err != nil {
-			return nil, err
-		}
-		c.Timeout = duration
+	if appConfig.SyncServerTimeout > 0 {
+		c.Timeout = time.Duration(appConfig.SyncServerTimeout) * time.Second
 	}
 	serverMap, err := http.Request(appConfig.GetServicesConfigURL(), c, &http.CallBack{
 		SuccessCallBack: SyncServerIPListSuccessCallBack,
diff --git a/env/config/config.go b/env/config/config.go
index cea37e49..ebfde508 100644
--- a/env/config/config.go
+++ b/env/config/config.go
@@ -29,17 +29,17 @@ import (
 
 var (
 	defaultNotificationID = int64(-1)
-	comma                 = ","
+	Comma                 = ","
 )
 
-//File 读写配置文件
+// File 读写配置文件
 type File interface {
 	Load(fileName string, unmarshal func([]byte) (interface{}, error)) (interface{}, error)
 
 	Write(content interface{}, configPath string) error
 }
 
-//AppConfig 配置文件
+// AppConfig 配置文件
 type AppConfig struct {
 	AppID             string `json:"appId"`
 	Cluster           string `json:"cluster"`
@@ -56,7 +56,7 @@ type AppConfig struct {
 	currentConnApolloConfig *CurrentApolloConfig
 }
 
-//ServerInfo 服务器信息
+// ServerInfo 服务器信息
 type ServerInfo struct {
 	AppName     string `json:"appName"`
 	InstanceID  string `json:"instanceId"`
@@ -64,19 +64,19 @@ type ServerInfo struct {
 	IsDown      bool   `json:"-"`
 }
 
-//GetIsBackupConfig whether backup config after fetch config from apollo
-//false : no
-//true : yes (default)
+// GetIsBackupConfig whether backup config after fetch config from apollo
+// false : no
+// true : yes (default)
 func (a *AppConfig) GetIsBackupConfig() bool {
 	return a.IsBackupConfig
 }
 
-//GetBackupConfigPath GetBackupConfigPath
+// GetBackupConfigPath GetBackupConfigPath
 func (a *AppConfig) GetBackupConfigPath() string {
 	return a.BackupConfigPath
 }
 
-//GetHost GetHost
+// GetHost GetHost
 func (a *AppConfig) GetHost() string {
 	u, err := url.Parse(a.IP)
 	if err != nil {
@@ -108,10 +108,10 @@ func (a *AppConfig) initAllNotifications(callback func(namespace string)) {
 	}
 }
 
-//SplitNamespaces 根据namespace字符串分割后，并执行callback函数
+// SplitNamespaces 根据namespace字符串分割后，并执行callback函数
 func SplitNamespaces(namespacesStr string, callback func(namespace string)) sync.Map {
 	namespaces := sync.Map{}
-	split := strings.Split(namespacesStr, comma)
+	split := strings.Split(namespacesStr, Comma)
 	for _, namespace := range split {
 		if callback != nil {
 			callback(namespace)
@@ -126,7 +126,7 @@ func (a *AppConfig) GetNotificationsMap() *notificationsMap {
 	return a.notificationsMap
 }
 
-//GetServicesConfigURL 获取服务器列表url
+// GetServicesConfigURL 获取服务器列表url
 func (a *AppConfig) GetServicesConfigURL() string {
 	return fmt.Sprintf("%sservices/config?appId=%s&ip=%s",
 		a.GetHost(),
diff --git a/protocol/auth/sign/sign.go b/protocol/auth/sign/sign.go
index 20bdf2dd..e729637a 100644
--- a/protocol/auth/sign/sign.go
+++ b/protocol/auth/sign/sign.go
@@ -22,6 +22,7 @@ import (
 	"crypto/sha1"
 	"encoding/base64"
 	"fmt"
+	"hash"
 	"net/url"
 	"strconv"
 	"time"
@@ -37,6 +38,17 @@ const (
 	question  = "?"
 )
 
+var (
+	h = sha1.New
+)
+
+// SetHash set hash function
+func SetHash(f func() hash.Hash) func() hash.Hash {
+	o := h
+	h = f
+	return o
+}
+
 // AuthSignature apollo 授权
 type AuthSignature struct {
 }
@@ -63,7 +75,7 @@ func (t *AuthSignature) HTTPHeaders(url string, appID string, secret string) map
 
 func signString(stringToSign string, accessKeySecret string) string {
 	key := []byte(accessKeySecret)
-	mac := hmac.New(sha1.New, key)
+	mac := hmac.New(h, key)
 	mac.Write([]byte(stringToSign))
 	return base64.StdEncoding.EncodeToString(mac.Sum(nil))
 }
diff --git a/protocol/auth/sign/sign_test.go b/protocol/auth/sign/sign_test.go
index 520790ad..9cc09913 100644
--- a/protocol/auth/sign/sign_test.go
+++ b/protocol/auth/sign/sign_test.go
@@ -18,8 +18,10 @@
 package sign
 
 import (
-	. "github.com/tevid/gohamcrest"
+	"crypto/sha256"
 	"testing"
+
+	. "github.com/tevid/gohamcrest"
 )
 
 const (
@@ -33,6 +35,13 @@ func TestSignString(t *testing.T) {
 	Assert(t, s, Equal("mcS95GXa7CpCjIfrbxgjKr0lRu8="))
 }
 
+func TestSetHash(t *testing.T) {
+	o := SetHash(sha256.New)
+	defer func() { SetHash(o) }()
+	s := signString(rawURL, secret)
+	Assert(t, s, Equal("XeIN8X6lAoujl6i88icVreaMYlBXeDco348545DkQDY="))
+}
+
 func TestUrl2PathWithQuery(t *testing.T) {
 
 	pathWithQuery := url2PathWithQuery(rawURL)
diff --git a/protocol/http/request.go b/protocol/http/request.go
index 1c4a00e1..51bb4b41 100644
--- a/protocol/http/request.go
+++ b/protocol/http/request.go
@@ -79,7 +79,7 @@ func getDefaultTransport(insecureSkipVerify bool) *http.Transport {
 	return defaultTransport
 }
 
-//CallBack 请求回调函数
+// CallBack 请求回调函数
 type CallBack struct {
 	SuccessCallBack   func([]byte, CallBack) (interface{}, error)
 	NotModifyCallBack func() error
@@ -87,7 +87,7 @@ type CallBack struct {
 	Namespace         string
 }
 
-//Request 建立网络请求
+// Request 建立网络请求
 func Request(requestURL string, connectionConfig *env.ConnectConfig, callBack *CallBack) (interface{}, error) {
 	client := &http.Client{}
 	//如有设置自定义超时时间即使用
@@ -175,6 +175,9 @@ func Request(requestURL string, connectionConfig *env.ConnectConfig, callBack *C
 				return nil, callBack.NotModifyCallBack()
 			}
 			return nil, nil
+		case http.StatusBadRequest, http.StatusUnauthorized, http.StatusNotFound, http.StatusMethodNotAllowed:
+			log.Errorf("Connect Apollo Server Fail, url:%s, StatusCode:%d", requestURL, res.StatusCode)
+			return nil, errors.New(fmt.Sprintf("Connect Apollo Server Fail, StatusCode:%d", res.StatusCode))
 		default:
 			log.Errorf("Connect Apollo Server Fail, url:%s, StatusCode:%d", requestURL, res.StatusCode)
 			// if error then sleep
@@ -190,7 +193,7 @@ func Request(requestURL string, connectionConfig *env.ConnectConfig, callBack *C
 	return nil, err
 }
 
-//RequestRecovery 可以恢复的请求
+// RequestRecovery 可以恢复的请求
 func RequestRecovery(appConfig config.AppConfig,
 	connectConfig *env.ConnectConfig,
 	callBack *CallBack) (interface{}, error) {
diff --git a/protocol/http/request_server_test.go b/protocol/http/request_server_test.go
index 74998578..71e3ca03 100644
--- a/protocol/http/request_server_test.go
+++ b/protocol/http/request_server_test.go
@@ -50,10 +50,10 @@ var servicesResponseStr = `[{
 
 var normalBackupConfigCount = 0
 
-//Normal response
-//First request will hold 5s and response http.StatusNotModified
-//Second request will hold 5s and response http.StatusNotModified
-//Second request will response [{"namespaceName":"application","notificationId":3}]
+// Normal response
+// First request will hold 5s and response http.StatusNotModified
+// Second request will hold 5s and response http.StatusNotModified
+// Second request will response [{"namespaceName":"application","notificationId":3}]
 func runNormalBackupConfigResponse() *httptest.Server {
 	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		normalBackupConfigCount++
@@ -84,7 +84,7 @@ func runNormalBackupConfigResponseWithHTTPS() *httptest.Server {
 	return ts
 }
 
-//wait long time then response
+// wait long time then response
 func runLongTimeResponse() *httptest.Server {
 	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		time.Sleep(10 * time.Second)
@@ -94,3 +94,11 @@ func runLongTimeResponse() *httptest.Server {
 
 	return ts
 }
+
+func runStatusCodeResponse(status int) *httptest.Server {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(status)
+	}))
+
+	return ts
+}
diff --git a/protocol/http/request_test.go b/protocol/http/request_test.go
index 66e2b30f..43774492 100644
--- a/protocol/http/request_test.go
+++ b/protocol/http/request_test.go
@@ -19,6 +19,7 @@ package http
 
 import (
 	"fmt"
+	"net/http"
 	"net/url"
 	"testing"
 	"time"
@@ -133,6 +134,43 @@ func TestCustomTimeout(t *testing.T) {
 	Assert(t, o, NilVal())
 }
 
+func TestFailFastStatusCode(t *testing.T) {
+	time.Sleep(1 * time.Second)
+
+	tests := []struct {
+		name   string
+		status int
+	}{
+		{name: "400", status: http.StatusBadRequest},
+		{name: "401", status: http.StatusUnauthorized},
+		{name: "404", status: http.StatusNotFound},
+		{name: "405", status: http.StatusMethodNotAllowed},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			testFailFastStatusCode(t, tt.status)
+		})
+	}
+}
+
+func testFailFastStatusCode(t *testing.T, status int) {
+	server := runStatusCodeResponse(status)
+	appConfig := getTestAppConfig()
+	appConfig.IP = server.URL
+
+	startTime := time.Now().Unix()
+	_, err := RequestRecovery(*appConfig, &env.ConnectConfig{
+		URI:     getConfigURLSuffix(appConfig, appConfig.NamespaceName),
+		IsRetry: true,
+	}, &CallBack{
+		SuccessCallBack: nil,
+	})
+	duration := time.Now().Unix() - startTime
+
+	Assert(t, err, NotNilVal())
+	Assert(t, int64(0), Equal(duration))
+}
+
 func mockIPList(t *testing.T, appConfigFunc func() config.AppConfig) {
 	time.Sleep(1 * time.Second)
 
@@ -159,7 +197,7 @@ func getConfigURLSuffix(config *config.AppConfig, namespaceName string) string {
 		utils.GetInternal())
 }
 
-//SyncServerIPListSuccessCallBack 同步服务器列表成功后的回调
+// SyncServerIPListSuccessCallBack 同步服务器列表成功后的回调
 func SyncServerIPListSuccessCallBack(responseBody []byte, callback CallBack) (o interface{}, err error) {
 	log.Debugf("get all server info: %s", string(responseBody))