diff --git a/cluster-autoscaler/cloudprovider/alicloud/alicloud_cloud_provider.go b/cluster-autoscaler/cloudprovider/alicloud/alicloud_cloud_provider.go
index 07c8a7a6bcea..d3dcdbc838d1 100644
--- a/cluster-autoscaler/cloudprovider/alicloud/alicloud_cloud_provider.go
+++ b/cluster-autoscaler/cloudprovider/alicloud/alicloud_cloud_provider.go
@@ -140,6 +140,11 @@ func (ali *aliCloudProvider) Cleanup() error {
 	return nil
 }
 
+// GetInstanceID gets the instance ID for the specified node.
+func (ali *aliCloudProvider) GetInstanceID(node *apiv1.Node) string {
+	return node.Spec.ProviderID
+}
+
 // AliRef contains a reference to ECS instance or .
 type AliRef struct {
 	ID     string
diff --git a/cluster-autoscaler/cloudprovider/aws/aws_cloud_provider.go b/cluster-autoscaler/cloudprovider/aws/aws_cloud_provider.go
index bddecab4ed9b..62fe61845771 100644
--- a/cluster-autoscaler/cloudprovider/aws/aws_cloud_provider.go
+++ b/cluster-autoscaler/cloudprovider/aws/aws_cloud_provider.go
@@ -127,6 +127,11 @@ func (aws *awsCloudProvider) Refresh() error {
 	return aws.awsManager.Refresh()
 }
 
+// GetInstanceID gets the instance ID for the specified node.
+func (aws *awsCloudProvider) GetInstanceID(node *apiv1.Node) string {
+	return node.Spec.ProviderID
+}
+
 // AwsRef contains a reference to some entity in AWS world.
 type AwsRef struct {
 	Name string
diff --git a/cluster-autoscaler/cloudprovider/azure/azure_agent_pool.go b/cluster-autoscaler/cloudprovider/azure/azure_agent_pool.go
index 7b8c92a6158b..6c9a7336016b 100644
--- a/cluster-autoscaler/cloudprovider/azure/azure_agent_pool.go
+++ b/cluster-autoscaler/cloudprovider/azure/azure_agent_pool.go
@@ -20,6 +20,7 @@ import (
 	"fmt"
 	"math/rand"
 	"sort"
+	"strings"
 	"sync"
 	"time"
 
@@ -132,7 +133,7 @@ func (as *AgentPool) GetVMIndexes() ([]int, map[int]string, error) {
 		}
 
 		indexes = append(indexes, index)
-		indexToVM[index] = "azure://" + *instance.ID
+		indexToVM[index] = "azure://" + strings.ToLower(*instance.ID)
 	}
 
 	sortedIndexes := sort.IntSlice(indexes)
@@ -242,7 +243,7 @@ func (as *AgentPool) GetVirtualMachines() (instances []compute.VirtualMachine, e
 
 		tags := instance.Tags
 		vmPoolName := tags["poolName"]
-		if vmPoolName == nil || *vmPoolName != as.Id() {
+		if vmPoolName == nil || !strings.EqualFold(*vmPoolName, as.Id()) {
 			continue
 		}
 
@@ -292,7 +293,7 @@ func (as *AgentPool) Belongs(node *apiv1.Node) (bool, error) {
 	if targetAsg == nil {
 		return false, fmt.Errorf("%s doesn't belong to a known agent pool", node.Name)
 	}
-	if targetAsg.Id() != as.Id() {
+	if !strings.EqualFold(targetAsg.Id(), as.Id()) {
 		return false, nil
 	}
 	return true, nil
@@ -315,7 +316,7 @@ func (as *AgentPool) DeleteInstances(instances []*azureRef) error {
 			return err
 		}
 
-		if asg != commonAsg {
+		if !strings.EqualFold(asg.Id(), commonAsg.Id()) {
 			return fmt.Errorf("cannot delete instance (%s) which don't belong to the same node pool (%q)", instance.GetKey(), commonAsg)
 		}
 	}
@@ -398,7 +399,7 @@ func (as *AgentPool) Nodes() ([]cloudprovider.Instance, error) {
 		}
 
 		// To keep consistent with providerID from kubernetes cloud provider, do not convert ID to lower case.
-		name := "azure://" + *instance.ID
+		name := "azure://" + strings.ToLower(*instance.ID)
 		nodes = append(nodes, cloudprovider.Instance{Id: name})
 	}
 
diff --git a/cluster-autoscaler/cloudprovider/azure/azure_cache.go b/cluster-autoscaler/cloudprovider/azure/azure_cache.go
index 345155ef335a..6f4fa56bb9ba 100644
--- a/cluster-autoscaler/cloudprovider/azure/azure_cache.go
+++ b/cluster-autoscaler/cloudprovider/azure/azure_cache.go
@@ -20,6 +20,7 @@ import (
 	"fmt"
 	"reflect"
 	"regexp"
+	"strings"
 	"sync"
 	"time"
 
@@ -63,7 +64,7 @@ func (m *asgCache) Register(asg cloudprovider.NodeGroup) bool {
 	defer m.mutex.Unlock()
 
 	for i := range m.registeredAsgs {
-		if existing := m.registeredAsgs[i]; existing.Id() == asg.Id() {
+		if existing := m.registeredAsgs[i]; strings.EqualFold(existing.Id(), asg.Id()) {
 			if reflect.DeepEqual(existing, asg) {
 				return false
 			}
@@ -94,7 +95,7 @@ func (m *asgCache) Unregister(asg cloudprovider.NodeGroup) bool {
 	updated := make([]cloudprovider.NodeGroup, 0, len(m.registeredAsgs))
 	changed := false
 	for _, existing := range m.registeredAsgs {
-		if existing.Id() == asg.Id() {
+		if strings.EqualFold(existing.Id(), asg.Id()) {
 			klog.V(1).Infof("Unregistered ASG %s", asg.Id())
 			changed = true
 			continue
@@ -117,7 +118,8 @@ func (m *asgCache) FindForInstance(instance *azureRef, vmType string) (cloudprov
 	m.mutex.Lock()
 	defer m.mutex.Unlock()
 
-	if m.notInRegisteredAsg[*instance] {
+	inst := azureRef{Name: strings.ToLower(instance.Name)}
+	if m.notInRegisteredAsg[inst] {
 		// We already know we don't own this instance. Return early and avoid
 		// additional calls.
 		return nil, nil
@@ -125,34 +127,37 @@ func (m *asgCache) FindForInstance(instance *azureRef, vmType string) (cloudprov
 
 	if vmType == vmTypeVMSS {
 		// Omit virtual machines not managed by vmss.
-		if ok := virtualMachineRE.Match([]byte(instance.Name)); ok {
+		if ok := virtualMachineRE.Match([]byte(inst.Name)); ok {
 			klog.V(3).Infof("Instance %q is not managed by vmss, omit it in autoscaler", instance.Name)
-			m.notInRegisteredAsg[*instance] = true
+			m.notInRegisteredAsg[inst] = true
 			return nil, nil
 		}
 	}
 
 	if vmType == vmTypeStandard {
 		// Omit virtual machines with providerID not in Azure resource ID format.
-		if ok := virtualMachineRE.Match([]byte(instance.Name)); !ok {
+		if ok := virtualMachineRE.Match([]byte(inst.Name)); !ok {
 			klog.V(3).Infof("Instance %q is not in Azure resource ID format, omit it in autoscaler", instance.Name)
-			m.notInRegisteredAsg[*instance] = true
+			m.notInRegisteredAsg[inst] = true
 			return nil, nil
 		}
 	}
 
-	if asg, found := m.instanceToAsg[*instance]; found {
+	// Look up caches for the instance.
+	if asg := m.getInstanceFromCache(inst.Name); asg != nil {
 		return asg, nil
 	}
 
+	// Not found, regenerate the cache and try again.
 	if err := m.regenerate(); err != nil {
-		return nil, fmt.Errorf("error while looking for ASG for instance %+v, error: %v", *instance, err)
+		return nil, fmt.Errorf("error while looking for ASG for instance %q, error: %v", instance.Name, err)
 	}
-	if config, found := m.instanceToAsg[*instance]; found {
-		return config, nil
+	if asg := m.getInstanceFromCache(inst.Name); asg != nil {
+		return asg, nil
 	}
 
-	m.notInRegisteredAsg[*instance] = true
+	// Add the instance to notInRegisteredAsg since it's unknown from Azure.
+	m.notInRegisteredAsg[inst] = true
 	return nil, nil
 }
 
@@ -179,3 +184,15 @@ func (m *asgCache) regenerate() error {
 	m.instanceToAsg = newCache
 	return nil
 }
+
+// Get node group from cache. nil would be return if not found.
+// Should be call with lock protected.
+func (m *asgCache) getInstanceFromCache(providerID string) cloudprovider.NodeGroup {
+	for instanceID, asg := range m.instanceToAsg {
+		if strings.EqualFold(instanceID.GetKey(), providerID) {
+			return asg
+		}
+	}
+
+	return nil
+}
diff --git a/cluster-autoscaler/cloudprovider/azure/azure_cloud_provider.go b/cluster-autoscaler/cloudprovider/azure/azure_cloud_provider.go
index 2a112ecd61fc..15dd6aa57357 100644
--- a/cluster-autoscaler/cloudprovider/azure/azure_cloud_provider.go
+++ b/cluster-autoscaler/cloudprovider/azure/azure_cloud_provider.go
@@ -19,6 +19,7 @@ package azure
 import (
 	"io"
 	"os"
+	"strings"
 
 	"k8s.io/klog"
 
@@ -110,6 +111,11 @@ func (azure *AzureCloudProvider) Refresh() error {
 	return azure.azureManager.Refresh()
 }
 
+// GetInstanceID gets the instance ID for the specified node.
+func (azure *AzureCloudProvider) GetInstanceID(node *apiv1.Node) string {
+	return strings.ToLower(node.Spec.ProviderID)
+}
+
 // azureRef contains a reference to some entity in Azure world.
 type azureRef struct {
 	Name string
diff --git a/cluster-autoscaler/cloudprovider/azure/azure_container_service_pool.go b/cluster-autoscaler/cloudprovider/azure/azure_container_service_pool.go
index 96c52e9147ee..cb382baa453b 100644
--- a/cluster-autoscaler/cloudprovider/azure/azure_container_service_pool.go
+++ b/cluster-autoscaler/cloudprovider/azure/azure_container_service_pool.go
@@ -78,7 +78,7 @@ func (agentPool *ContainerServiceAgentPool) GetAKSAgentPool(agentProfiles *[]con
 	for _, value := range *agentProfiles {
 		profileName := *value.Name
 		klog.V(5).Infof("AKS AgentPool profile name: %s", profileName)
-		if profileName == (agentPool.azureRef.Name) {
+		if strings.EqualFold(profileName, agentPool.azureRef.Name) {
 			return &value
 		}
 	}
@@ -92,7 +92,7 @@ func (agentPool *ContainerServiceAgentPool) GetACSAgentPool(agentProfiles *[]con
 	for _, value := range *agentProfiles {
 		profileName := *value.Name
 		klog.V(5).Infof("ACS AgentPool profile name: %s", profileName)
-		if profileName == (agentPool.azureRef.Name) {
+		if strings.EqualFold(profileName, agentPool.azureRef.Name) {
 			return &value
 		}
 	}
@@ -105,7 +105,7 @@ func (agentPool *ContainerServiceAgentPool) GetACSAgentPool(agentProfiles *[]con
 		profileName := *value.Name
 		poolName := agentPool.azureRef.Name + "pool0"
 		klog.V(5).Infof("Workaround match check - ACS AgentPool Profile: %s <=> Poolname: %s", profileName, poolName)
-		if profileName == poolName {
+		if strings.EqualFold(profileName, poolName) {
 			return &value
 		}
 	}
@@ -270,7 +270,7 @@ func (agentPool *ContainerServiceAgentPool) SetNodeCount(count int) (err error)
 func (agentPool *ContainerServiceAgentPool) GetProviderID(name string) string {
 	//TODO: come with a generic way to make it work with provider id formats
 	// in different version of k8s.
-	return "azure://" + name
+	return "azure://" + strings.ToLower(name)
 }
 
 //GetName extracts the name of the node (a format which underlying cloud service understands)
@@ -285,7 +285,7 @@ func (agentPool *ContainerServiceAgentPool) GetName(providerID string) (string,
 		return "", err
 	}
 	for _, vm := range vms {
-		if strings.Compare(*vm.ID, providerID) == 0 {
+		if strings.EqualFold(*vm.ID, providerID) {
 			return *vm.Name, nil
 		}
 	}
@@ -398,7 +398,7 @@ func (agentPool *ContainerServiceAgentPool) IsContainerServiceNode(tags map[stri
 	poolName := tags["poolName"]
 	if poolName != nil {
 		klog.V(5).Infof("Matching agentPool name: %s with tag name: %s", agentPool.azureRef.Name, *poolName)
-		if *poolName == agentPool.azureRef.Name {
+		if strings.EqualFold(*poolName, agentPool.azureRef.Name) {
 			return true
 		}
 	}
diff --git a/cluster-autoscaler/cloudprovider/azure/azure_fakes.go b/cluster-autoscaler/cloudprovider/azure/azure_fakes.go
index dd1f532bb88c..395f01a4c0b4 100644
--- a/cluster-autoscaler/cloudprovider/azure/azure_fakes.go
+++ b/cluster-autoscaler/cloudprovider/azure/azure_fakes.go
@@ -30,7 +30,7 @@ import (
 )
 
 const (
-	fakeVirtualMachineScaleSetVMID = "/subscriptions/test-subscription-id/resourceGroups/test-asg/providers/Microsoft.Compute/virtualMachineScaleSets/agents/virtualMachines/0"
+	fakeVirtualMachineScaleSetVMID = "/subscriptions/test-subscription-id/resourcegroups/test-asg/providers/microsoft.compute/virtualmachinescalesets/agents/virtualmachines/0"
 )
 
 // VirtualMachineScaleSetsClientMock mocks for VirtualMachineScaleSetsClient.
diff --git a/cluster-autoscaler/cloudprovider/azure/azure_scale_set.go b/cluster-autoscaler/cloudprovider/azure/azure_scale_set.go
index b3a760836957..72b555afba33 100644
--- a/cluster-autoscaler/cloudprovider/azure/azure_scale_set.go
+++ b/cluster-autoscaler/cloudprovider/azure/azure_scale_set.go
@@ -48,8 +48,6 @@ type ScaleSet struct {
 	mutex       sync.Mutex
 	lastRefresh time.Time
 	curSize     int64
-	// virtualMachines holds a list of vmss instances (instanceID -> resourceID).
-	virtualMachines map[string]string
 }
 
 // NewScaleSet creates a new NewScaleSet.
@@ -58,11 +56,10 @@ func NewScaleSet(spec *dynamic.NodeGroupSpec, az *AzureManager) (*ScaleSet, erro
 		azureRef: azureRef{
 			Name: spec.Name,
 		},
-		minSize:         spec.MinSize,
-		maxSize:         spec.MaxSize,
-		manager:         az,
-		curSize:         -1,
-		virtualMachines: make(map[string]string),
+		minSize: spec.MinSize,
+		maxSize: spec.MaxSize,
+		manager: az,
+		curSize: -1,
 	}
 
 	return scaleSet, nil
@@ -196,55 +193,24 @@ func (scaleSet *ScaleSet) IncreaseSize(delta int) error {
 // GetScaleSetVms returns list of nodes for the given scale set.
 // Note that the list results is not used directly because their resource ID format
 // is not consistent with Get results.
-// TODO(feiskyer): use list results directly after the issue fixed in Azure VMSS API.
 func (scaleSet *ScaleSet) GetScaleSetVms() ([]string, error) {
 	ctx, cancel := getContextWithCancel()
 	defer cancel()
 
 	resourceGroup := scaleSet.manager.config.ResourceGroup
-	result, err := scaleSet.manager.azClient.virtualMachineScaleSetVMsClient.List(ctx, resourceGroup, scaleSet.Name, "", "", "")
+	vmList, err := scaleSet.manager.azClient.virtualMachineScaleSetVMsClient.List(ctx, resourceGroup, scaleSet.Name, "", "", "")
 	if err != nil {
 		klog.Errorf("VirtualMachineScaleSetVMsClient.List failed for %s: %v", scaleSet.Name, err)
 		return nil, err
 	}
 
-	instanceIDs := make([]string, 0)
-	for _, vm := range result {
-		instanceIDs = append(instanceIDs, *vm.InstanceID)
-	}
-
 	allVMs := make([]string, 0)
-	for _, instanceID := range instanceIDs {
-		// Get from cache first.
-		if v, ok := scaleSet.virtualMachines[instanceID]; ok {
-			allVMs = append(allVMs, v)
-			continue
-		}
-
-		// Not in cache, get from Azure API.
-		getCtx, getCancel := getContextWithCancel()
-		defer getCancel()
-		vm, err := scaleSet.manager.azClient.virtualMachineScaleSetVMsClient.Get(getCtx, resourceGroup, scaleSet.Name, instanceID)
-		if err != nil {
-			exists, realErr := checkResourceExistsFromError(err)
-			if realErr != nil {
-				klog.Errorf("Failed to get VirtualMachineScaleSetVM by (%s,%s), error: %v", scaleSet.Name, instanceID, err)
-				return nil, realErr
-			}
-
-			if !exists {
-				klog.Warningf("Couldn't find VirtualMachineScaleSetVM by (%s,%s), assuming it has been removed", scaleSet.Name, instanceID)
-				continue
-			}
-		}
-
+	for _, vm := range vmList {
 		// The resource ID is empty string, which indicates the instance may be in deleting state.
 		if len(*vm.ID) == 0 {
 			continue
 		}
 
-		// Save into cache.
-		scaleSet.virtualMachines[instanceID] = *vm.ID
 		allVMs = append(allVMs, *vm.ID)
 	}
 
@@ -294,7 +260,7 @@ func (scaleSet *ScaleSet) Belongs(node *apiv1.Node) (bool, error) {
 	if targetAsg == nil {
 		return false, fmt.Errorf("%s doesn't belong to a known scale set", node.Name)
 	}
-	if targetAsg.Id() != scaleSet.Id() {
+	if !strings.EqualFold(targetAsg.Id(), scaleSet.Id()) {
 		return false, nil
 	}
 	return true, nil
@@ -320,7 +286,7 @@ func (scaleSet *ScaleSet) DeleteInstances(instances []*azureRef) error {
 			return err
 		}
 
-		if asg != commonAsg {
+		if !strings.EqualFold(asg.Id(), commonAsg.Id()) {
 			return fmt.Errorf("cannot delete instance (%s) which don't belong to the same Scale Set (%q)", instance.Name, commonAsg)
 		}
 
@@ -490,7 +456,7 @@ func (scaleSet *ScaleSet) Nodes() ([]cloudprovider.Instance, error) {
 
 	instances := make([]cloudprovider.Instance, 0, len(vms))
 	for i := range vms {
-		name := "azure://" + vms[i]
+		name := "azure://" + strings.ToLower(vms[i])
 		instances = append(instances, cloudprovider.Instance{Id: name})
 	}
 
diff --git a/cluster-autoscaler/cloudprovider/azure/azure_scale_set_test.go b/cluster-autoscaler/cloudprovider/azure/azure_scale_set_test.go
index f6f9b6c8ca07..d9d9451ea44a 100644
--- a/cluster-autoscaler/cloudprovider/azure/azure_scale_set_test.go
+++ b/cluster-autoscaler/cloudprovider/azure/azure_scale_set_test.go
@@ -33,10 +33,9 @@ func newTestScaleSet(manager *AzureManager, name string) *ScaleSet {
 		azureRef: azureRef{
 			Name: name,
 		},
-		manager:         manager,
-		minSize:         1,
-		maxSize:         5,
-		virtualMachines: make(map[string]string),
+		manager: manager,
+		minSize: 1,
+		maxSize: 5,
 	}
 }
 
@@ -92,7 +91,7 @@ func TestBelongs(t *testing.T) {
 
 	invalidNode := &apiv1.Node{
 		Spec: apiv1.NodeSpec{
-			ProviderID: "azure:///subscriptions/test-subscrition-id/resourceGroups/invalid-asg/providers/Microsoft.Compute/virtualMachineScaleSets/agents/virtualMachines/0",
+			ProviderID: "azure:///subscriptions/test-subscrition-id/resourcegroups/invalid-asg/providers/microsoft.compute/virtualmachinescalesets/agents/virtualmachines/0",
 		},
 	}
 	_, err := scaleSet.Belongs(invalidNode)
@@ -183,10 +182,6 @@ func TestScaleSetNodes(t *testing.T) {
 	ss, ok := group.(*ScaleSet)
 	assert.True(t, ok)
 	assert.NotNil(t, ss)
-	assert.Equal(t, ss.virtualMachines, map[string]string{
-		"0": fakeVirtualMachineScaleSetVMID,
-	})
-
 	instances, err := group.Nodes()
 	assert.NoError(t, err)
 	assert.Equal(t, len(instances), 1)
diff --git a/cluster-autoscaler/cloudprovider/baiducloud/baiducloud_cloud_provider.go b/cluster-autoscaler/cloudprovider/baiducloud/baiducloud_cloud_provider.go
index f99e60c131f5..d6e16efd4be6 100644
--- a/cluster-autoscaler/cloudprovider/baiducloud/baiducloud_cloud_provider.go
+++ b/cluster-autoscaler/cloudprovider/baiducloud/baiducloud_cloud_provider.go
@@ -196,6 +196,11 @@ func (baiducloud *baiducloudCloudProvider) Refresh() error {
 	return nil
 }
 
+// GetInstanceID gets the instance ID for the specified node.
+func (baiducloud *baiducloudCloudProvider) GetInstanceID(node *apiv1.Node) string {
+	return node.Spec.ProviderID
+}
+
 // BaiducloudRef contains a reference to some entity in baiducloud world.
 type BaiducloudRef struct {
 	Name string
diff --git a/cluster-autoscaler/cloudprovider/cloud_provider.go b/cluster-autoscaler/cloudprovider/cloud_provider.go
index 8eb252efe31d..0187c2178b14 100644
--- a/cluster-autoscaler/cloudprovider/cloud_provider.go
+++ b/cluster-autoscaler/cloudprovider/cloud_provider.go
@@ -56,6 +56,9 @@ type CloudProvider interface {
 	// GetResourceLimiter returns struct containing limits (max, min) for resources (cores, memory etc.).
 	GetResourceLimiter() (*ResourceLimiter, error)
 
+	// GetInstanceID gets the instance ID for the specified node.
+	GetInstanceID(node *apiv1.Node) string
+
 	// Cleanup cleans up open resources before the cloud provider is destroyed, i.e. go routines etc.
 	Cleanup() error
 
diff --git a/cluster-autoscaler/cloudprovider/gce/gce_cloud_provider.go b/cluster-autoscaler/cloudprovider/gce/gce_cloud_provider.go
index 7741c612809c..80974b37c671 100644
--- a/cluster-autoscaler/cloudprovider/gce/gce_cloud_provider.go
+++ b/cluster-autoscaler/cloudprovider/gce/gce_cloud_provider.go
@@ -114,6 +114,11 @@ func (gce *GceCloudProvider) Refresh() error {
 	return gce.gceManager.Refresh()
 }
 
+// GetInstanceID gets the instance ID for the specified node.
+func (gce *GceCloudProvider) GetInstanceID(node *apiv1.Node) string {
+	return node.Spec.ProviderID
+}
+
 // GceRef contains s reference to some entity in GCE world.
 type GceRef struct {
 	Project string
diff --git a/cluster-autoscaler/cloudprovider/gke/gke_cloud_provider.go b/cluster-autoscaler/cloudprovider/gke/gke_cloud_provider.go
index a6ce8f3b3f55..76cc7fb8d68a 100644
--- a/cluster-autoscaler/cloudprovider/gke/gke_cloud_provider.go
+++ b/cluster-autoscaler/cloudprovider/gke/gke_cloud_provider.go
@@ -213,6 +213,11 @@ func (gke *GkeCloudProvider) GetNodeLocations() []string {
 	return gke.gkeManager.GetNodeLocations()
 }
 
+// GetInstanceID gets the instance ID for the specified node.
+func (gke *GkeCloudProvider) GetInstanceID(node *apiv1.Node) string {
+	return node.Spec.ProviderID
+}
+
 // MigSpec contains information about what machines in a MIG look like.
 type MigSpec struct {
 	MachineType    string
diff --git a/cluster-autoscaler/cloudprovider/kubemark/kubemark_linux.go b/cluster-autoscaler/cloudprovider/kubemark/kubemark_linux.go
index 8b556cf66628..eddeeb13c7ae 100644
--- a/cluster-autoscaler/cloudprovider/kubemark/kubemark_linux.go
+++ b/cluster-autoscaler/cloudprovider/kubemark/kubemark_linux.go
@@ -135,6 +135,11 @@ func (kubemark *KubemarkCloudProvider) Refresh() error {
 	return nil
 }
 
+// GetInstanceID gets the instance ID for the specified node.
+func (kubemark *KubemarkCloudProvider) GetInstanceID(node *apiv1.Node) string {
+	return node.Spec.ProviderID
+}
+
 // Cleanup cleans up all resources before the cloud provider is removed
 func (kubemark *KubemarkCloudProvider) Cleanup() error {
 	return nil
diff --git a/cluster-autoscaler/cloudprovider/kubemark/kubemark_other.go b/cluster-autoscaler/cloudprovider/kubemark/kubemark_other.go
index f7b0afd32cbc..47af42565659 100644
--- a/cluster-autoscaler/cloudprovider/kubemark/kubemark_other.go
+++ b/cluster-autoscaler/cloudprovider/kubemark/kubemark_other.go
@@ -85,6 +85,11 @@ func (kubemark *KubemarkCloudProvider) Refresh() error {
 	return cloudprovider.ErrNotImplemented
 }
 
+// GetInstanceID gets the instance ID for the specified node.
+func (kubemark *KubemarkCloudProvider) GetInstanceID(node *apiv1.Node) string {
+	return ""
+}
+
 // Cleanup cleans up all resources before the cloud provider is removed
 func (kubemark *KubemarkCloudProvider) Cleanup() error {
 	return cloudprovider.ErrNotImplemented
diff --git a/cluster-autoscaler/cloudprovider/mocks/CloudProvider.go b/cluster-autoscaler/cloudprovider/mocks/CloudProvider.go
index 6a6c9d948d2f..ce4cdd186f91 100644
--- a/cluster-autoscaler/cloudprovider/mocks/CloudProvider.go
+++ b/cluster-autoscaler/cloudprovider/mocks/CloudProvider.go
@@ -201,3 +201,17 @@ func (_m *CloudProvider) Refresh() error {
 
 	return r0
 }
+
+// GetInstanceID gets the instance ID for the specified node.
+func (_m *CloudProvider) GetInstanceID(node *v1.Node) string {
+	ret := _m.Called()
+
+	var r0 string
+	if rf, ok := ret.Get(0).(func() string); ok {
+		r0 = rf()
+	} else {
+		r0 = ret.Get(0).(string)
+	}
+
+	return r0
+}
diff --git a/cluster-autoscaler/cloudprovider/test/test_cloud_provider.go b/cluster-autoscaler/cloudprovider/test/test_cloud_provider.go
index 92818131e82e..97e2a65a5dff 100644
--- a/cluster-autoscaler/cloudprovider/test/test_cloud_provider.go
+++ b/cluster-autoscaler/cloudprovider/test/test_cloud_provider.go
@@ -224,6 +224,11 @@ func (tcp *TestCloudProvider) Refresh() error {
 	return nil
 }
 
+// GetInstanceID gets the instance ID for the specified node.
+func (tcp *TestCloudProvider) GetInstanceID(node *apiv1.Node) string {
+	return node.Spec.ProviderID
+}
+
 // TestNodeGroup is a node group used by TestCloudProvider.
 type TestNodeGroup struct {
 	sync.Mutex
diff --git a/cluster-autoscaler/clusterstate/clusterstate.go b/cluster-autoscaler/clusterstate/clusterstate.go
index 390ec2f6eeea..02e5b2017a03 100644
--- a/cluster-autoscaler/clusterstate/clusterstate.go
+++ b/cluster-autoscaler/clusterstate/clusterstate.go
@@ -281,7 +281,7 @@ func (csr *ClusterStateRegistry) UpdateNodes(nodes []*apiv1.Node, nodeInfosForGr
 	if err != nil {
 		return err
 	}
-	notRegistered := getNotRegisteredNodes(nodes, cloudProviderNodeInstances, currentTime)
+	notRegistered := getNotRegisteredNodes(csr.cloudProvider, nodes, cloudProviderNodeInstances, currentTime)
 
 	csr.Lock()
 	defer csr.Unlock()
@@ -932,10 +932,10 @@ func getCloudProviderNodeInstances(cloudProvider cloudprovider.CloudProvider) (m
 }
 
 // Calculates which of the existing cloud provider nodes are not registered in Kubernetes.
-func getNotRegisteredNodes(allNodes []*apiv1.Node, cloudProviderNodeInstances map[string][]cloudprovider.Instance, time time.Time) []UnregisteredNode {
+func getNotRegisteredNodes(cloudProvider cloudprovider.CloudProvider, allNodes []*apiv1.Node, cloudProviderNodeInstances map[string][]cloudprovider.Instance, time time.Time) []UnregisteredNode {
 	registered := sets.NewString()
 	for _, node := range allNodes {
-		registered.Insert(node.Spec.ProviderID)
+		registered.Insert(cloudProvider.GetInstanceID(node))
 	}
 	notRegistered := make([]UnregisteredNode, 0)
 	for _, instances := range cloudProviderNodeInstances {