> ## Documentation Index > Fetch the complete documentation index at: https://notes.kodekloud.com/llms.txt > Use this file to discover all available pages before exploring further. # Solution Namespaces optional > This article provides a step-by-step guide for completing a Kubernetes lab exercise on namespaces, covering tasks like identifying namespaces and configuring inter-namespace communication. In this article, we present a step-by-step guide to complete the Kubernetes lab exercise on namespaces. Follow along as we cover tasks ranging from identifying namespaces to configuring inter-namespace communication for applications and services. ## Identifying the Number of Namespaces To begin, determine how many namespaces exist on the system. Run the following command to list all namespaces: ```bash theme={null} kubectl get namespaces ``` Alternatively, you can use the shorthand version: ```bash theme={null} kubectl get ns ``` For example, you might see an output similar to: ```bash theme={null} NAME STATUS AGE default Active 6m50s kube-system Active 6m49s kube-public Active 6m49s kube-node-lease Active 6m49s finance Active 27s marketing Active 27s dev Active 27s prod Active 27s manufacturing Active 27s research Active 27s ``` This output indicates that there are 10 namespaces available. ## Listing Pods in a Specific Namespace Next, check the number of pods running within the research namespace. Use one of the following commands: ```bash theme={null} kubectl get pods --namespace=research ``` Or with the shorthand option: ```bash theme={null} kubectl get pods -n research ``` The expected outcome should display that there are two pods in the research namespace. ## Creating a Pod in the Finance Namespace To create a pod in the finance namespace, you can use the `kubectl run` command with the appropriate namespace flag. For instance, running the following command without specifying a namespace creates the pod in the default namespace: ```bash theme={null} kubectl run redis --image=redis ``` To instead create the pod in the finance namespace, include the `-n` flag as shown below: ```bash theme={null} kubectl run redis --image=redis -n finance ``` After executing this command, verify the pod creation by listing pods in the finance namespace: ```bash theme={null} kubectl get pods -n finance ``` A sample output might resemble: ```bash theme={null} NAME READY STATUS RESTARTS AGE payroll 1/1 Running 0 2m20s redis 0/1 ContainerCreating 0 8s ``` ## Determining the Namespace of the Blue Pod To identify which namespace contains the blue pod, you can either inspect pods in each namespace individually or use the `--all-namespaces` flag to list every pod cluster-wide. First, inspect a specific namespace using: ```bash theme={null} kubectl get pods -n finance ``` And list all namespaces with: ```bash theme={null} kubectl get ns ``` For a more efficient search, list pods across all namespaces: ```bash theme={null} kubectl get pods --all-namespaces ``` A sample output might look like this: ```bash theme={null} NAMESPACE NAME READY STATUS RESTARTS AGE kube-system local-path-provisioner-6c79684f77-j5qx 1/1 Running 0 9m5s kube-system corends-5788995cd-bkj56 1/1 Running 0 9m5s kube-system helm-install-traefik-crd-d2f67 0/1 Completed 0 9m7s kube-system metrics-server-7cd5fc6b67-kdgzb 1/1 Running 0 9m5s kube-system helm-install-traefik-c987s 1/1 Running 0 9m5s kube-system svcvlc-traefik-jptsh 2/2 Running 0 8m30s kube-system traefik-6bb96f9fbd8-w9zxr 1/1 Running 0 3m3s marketing redis-db 1/1 Running 0 3m3s dev red-app 1/1 Running 0 3m3s finance payroll 1/1 Running 0 3m3s marketing blue 0/1 CrashLoopBackOff 4 (80s ago) 3m3s research dna-1 1/1 Running 0 3m3s research dna-2 0/1 CrashLoopBackOff 4 (70s ago) 3m3s finance redis 1/1 Running 0 51s ``` From this output, notice that the blue pod is located in the **marketing** namespace. ## Accessing the Blue Application and Its Database Service The blue application is a simple web-based tool used for connectivity tests. When launched from the terminal interface, it opens up a browser window that displays the application. The next step is to determine which DNS name the blue application should use to access the database (DB) service within its own namespace. To verify, first list the pods and services in the marketing namespace. List the pods: ```bash theme={null} kubectl get pods -n marketing ``` Sample output: ```bash theme={null} NAME READY STATUS RESTARTS AGE redis-db 1/1 Running 0 4m14s blue 1/1 Running 0 4m14s ``` Then, list the services in the same namespace: ```bash theme={null} kubectl get svc -n marketing ``` Sample output: ```bash theme={null} NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE blue-service NodePort 10.43.82.162 8080:30082/TCP 4m27s db-service NodePort 10.43.134.33 6379:30758/TCP 4m27s ``` > **Note: DNS Access** > When connecting to services within the same namespace, referencing the service by its name (e.g., "db-service") is sufficient due to Kubernetes' internal DNS resolution. After configuring the connection, verify that the connectivity test confirms the correct host name and port settings. ![The image shows a "Connectivity Test" interface with a host name and port, indicating a successful connection.](https://kodekloud.com/kk-media/image/upload/v1752871204/notes-assets/images/Certified-Kubernetes-Application-Developer-CKAD-Solution-Namespaces-optional/frame_350.jpg) ## Accessing the DB Service in a Different Namespace Now, consider how to access the DB service when it is located in a different namespace from the blue application. Assume that there is a service named "db-service" in both the marketing and dev namespaces. First, verify the services in these namespaces. In the marketing namespace: ```bash theme={null} kubectl get svc -n marketing ``` Output example: ```bash theme={null} NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE blue-service NodePort 10.43.82.162 8080:30082/TCP 4m27s db-service NodePort 10.43.134.33 6379:30758/TCP 4m27s ``` In the dev namespace: ```bash theme={null} kubectl get svc -n dev ``` Output example: ```bash theme={null} NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE db-service ClusterIP 10.43.252.9 6379/TCP 5m22s ``` To access the DB service in the dev namespace from an application situated in another namespace, use the fully qualified domain name (FQDN) that follows this format: db-service.dev.svc.cluster.local This format includes the service name, the namespace, and the cluster domain, ensuring accurate DNS resolution across namespaces. > **Tip for Inter-Namespace Communication:** > Using the FQDN is essential when accessing services from a different namespace. This ensures clear resolution, especially in clusters with multiple services sharing the same name. Testing the connection with this FQDN should confirm that the blue application can successfully communicate with the DB service in the dev namespace. At this point, you have successfully completed all the lab tasks related to Kubernetes namespaces. Right. That's the end of the lab.