I configure my services with type ClusterIP. And I want to make them communicated.

Service

apiVersion: v1
kind: Service
metadata:
 labels:
  app: app-backend-deployment
 name: app-backend
spec:
 type: ClusterIP
 ports:
 - port: 8020
   protocol: TCP
   targetPort: 8100
 selector:
  app: app-backend

Deployment

apiVersion: apps/v1
kind: Deployment
metadata:
 labels:
  app: app-backend
 name: app-backend-deployment
spec:
 replicas: 1
 selector:
    matchLabels:
      app: app-backend
 template:
    metadata:
      labels:
        app: app-backend
    spec:
     containers:
     - name: app-backend
       image: app-backend
       ports:
       - containerPort: 8100
       imagePullPolicy: Never

ConfigMap

apiVersion: v1
kind: ConfigMap
metadata:
  name: backend-conf # name of configMap
data:
  BACKEND_SERVICE_HOST: app-backend:8020

And that is what I pass to the frontend service, and I want to make a REST call through the DNS name for example http://app-backend:8020/get/1. But like I see in the console app cannot resolve DNS name net::ERR_NAME_NOT_RESOLVED.

I also check pod nslookup:

busybox nslookup app-backend.default.svc.cluster.local
Server:         10.96.0.10
Address:        10.96.0.10:53

Name:   app-backend.default.svc.cluster.local
Address: 10.106.41.36

And compare it to

kubectl describe svc app-backend
Name:              app-backend
Namespace:         default
Labels:            app=app-backend-deployment
Annotations:       kubectl.kubernetes.io/last-applied-configuration:
                     {"...
Selector:          app=app-backend
Type:              ClusterIP
IP:                10.106.41.36
Port:              <unset>  8020/TCP
TargetPort:        8100/TCP

And like you can see there is the same IP on Address but I don't know and where to look what is wrong why dns resolver doesn't work. kubectl version Client "v1.15.5", Server Version:"v1.17.3",