> ## 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 Explore Environment optional > This guide answers questions about your Kubernetes cluster environment and shows how to retrieve details using various commands. In this guide, we will answer several questions regarding your Kubernetes cluster environment and illustrate how to retrieve the required details using various commands. *** ## 1. How Many Nodes Are in the Cluster? To find out how many nodes are part of your cluster, run: ```bash theme={null} kubectl get nodes ``` The command outputs a list of nodes. In this example, there are two nodes—one functioning as the control plane and another as a worker node. ```bash theme={null} controlplane ~ ➜ kubectl get nodes NAME STATUS ROLES AGE VERSION controlplane Ready control-plane 20m v1.26.0 node01 Ready 19m v1.26.0 controlplane ~ ➜ ``` *** ## 2. What Is the Internal IP Address of the Control Plane Node? Use the `-o wide` option with `kubectl get nodes` to view additional details, including the internal IP address: ```bash theme={null} kubectl get nodes -o wide ``` Locate the control plane node entry. In this sample output, the internal IP for the control plane is `192.5.114.3`. ```bash theme={null} controlplane ~ ⟶ kubectl get nodes -o wide NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINERS controlplane Ready control-plane 20m v1.26.0 192.5.114.3 Ubuntu 20.04.5 LTS 5.4.0-1100-gcp containerd node01 Ready 19m v1.26.0 192.5.114.6 Ubuntu 20.04.5 LTS 5.4.0-1100-gcp containerd ``` *** ## 3. Which Network Interface Is Configured for Cluster Connectivity on the Control Plane Node? To determine which network interface is used for cluster connectivity, run: ```bash theme={null} ip address ``` Review the output and look for the interface that shows the relevant IP address (in this case, an IP ending in `.3`). In the sample provided, the `eth0` interface has the correct binding. ```bash theme={null} controlplane ~ ⌁ ip address 1: lo: mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever 2: flannel.1: mtu 1450 qdisc noqueue state UNKNOWN group default link/ether 7a:88:3a:71:47:f7 brd ff:ff:ff:ff:ff:ff inet 10.244.1.1/32 scope global flannel.1 valid_lft forever preferred_lft forever 3: cni0: mtu 1450 qdisc noqueue state UP group default link/ether 4a:ba:dc:3d:2c:7b brd ff:ff:ff:ff:ff:ff inet 10.244.0.2/24 scope global cni0 valid_lft forever preferred_lft forever 4: veth38a0c647: mtu 1450 qdisc noqueue master cni0 state UP group default link/ether 4e:41:6e:6b:6d:bb brd ff:ff:ff:ff:ff:ff 5: veth0f5b312d: mtu 1450 qdisc noqueue master cni0 state UP group default link/ether 5e:9b:da:c5:43:fa brd ff:ff:ff:ff:ff:ff inet 192.168.0.2/24 brd 192.168.0.255 scope global eth0 valid_lft forever preferred_lft forever 6: eth0@if49800f: mtu 1500 qdisc noqueue master cni0 state UP group default link/ether 56:1b:87:f1:9a:05 brd ff:ff:ff:ff:ff:ff inet 172.25.0.42/24 brd 172.25.0.255 scope global eth1 valid_lft forever preferred_lft forever ``` The interface selected for cluster connectivity is the one with the IP address matching that of the control plane node. *** ## 4. What Is the MAC Address of the Control Plane Node’s Network Interface? Once you know the interface name (in this example, `eth0`), you can use the following command to display its MAC address: ```bash theme={null} ip address show eth0 ``` The MAC address appears in the output; for instance, you might see a value like `5e:9b:da:c5:43:fa`. Use this value as needed. *** ## 5. What Is the IP Address Assigned to Node One? To discover the internal IP address of the worker node (node one), run: ```bash theme={null} kubectl get nodes -o wide ``` Examine the entry corresponding to `node01`. In the sample output below, the worker node's internal IP address is `192.5.114.6`. ```bash theme={null} NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME controlplane Ready control-plane 21m v1.26.0 192.5.114.3 Ubuntu 20.04.5 LTS 5.4.0-1100-gcp containerd node01 Ready 21m v1.26.0 192.5.114.6 Ubuntu 20.04.5 LTS 5.4.0-1100-gcp containerd ``` *** ## 6. What Is the MAC Address Assigned to Node One? To retrieve node one's MAC address, SSH into node one and execute: ```bash theme={null} ip address ``` Scroll through the output until you find the interface associated with the internal IP (e.g., matching `192.5.114.6`). The corresponding MAC address—in this case, `02:42:c0:05:72:06`—is the answer. ```bash theme={null} root@node01 ~ # ip address 1: lo: mtu 65536 qdisc noqueue state UNKNOWN group default link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo valid_lft forever preferred_lft forever 2: flannel.1: mtu 1450 qdisc noqueue state UNKNOWN group default link/ether 36:1c:bg:bf:ef:db brd ff:ff:ff:ff:ff:ff inet 10.244.0.1/32 scope global flannel.1 valid_lft forever preferred_lft forever 598: eth0@if599: mtu 1500 qdisc noqueue state UP group default link/ether 02:42:c0:05:72:06 brd ff:ff:ff:ff:ff:ff link-netnsid 0 inet 192.5.114.6/24 brd 192.5.114.255 scope global eth0 valid_lft forever preferred_lft forever 600: eth1@if601: mtu 1500 qdisc noqueue state UP group default link/ether 02:42:ac:19:00:28 brd ff:ff:ff:ff:ff:ff link-netnsid 1 inet 172.25.0.32/24 brd 172.25.0.255 scope global eth1 valid_lft forever preferred_lft forever ``` *** ## 7. What Is the Container Runtime’s Bridge Interface on the Host? ContainerD commonly uses a CNI plugin to manage networking, which creates a bridge interface. Typically, this interface is named `cni0`. Confirm by listing all network interfaces: ```bash theme={null} ip address ``` In the output, the `cni0` interface is visible and serves as the bridge for container connectivity. ```bash theme={null} controlplane ~ ⟶ ip address ... 3: cni0: mtu 1450 qdisc noqueue state UP group default link/ether 2a:4d:3a:9c:2f:a2 brd ff:ff:ff:ff:ff:ff inet 10.244.0.2/24 brd 10.244.0.255 scope global cni0 valid_lft forever preferred_lft forever ... ``` The `cni0` bridge interface is essential for container networking. Ensure your CNI configuration is correct for proper connectivity. *** ## 8. What Is the State of Interface cni0? To check the current state of the `cni0` interface, run: ```bash theme={null} ip address show cni0 ``` The output will display details, including the interface state. In the provided output, the state is `UP`. ```bash theme={null} controlplane ~ ➜ ip address show cni0 3: cni0: mtu 1450 qdisc noqueue master cni0 state UP group default link/ether ba:4d:3a:9c:1a:20 brd ff:ff:ff:ff:ff:ff inet 10.244.0.2/24 brd 10.244.0.255 scope global cni0 valid_lft forever preferred_lft forever ``` *** ## 9. What Is the Default Gateway Used When Pinging Google from the Control Plane Node? To identify the route taken for external traffic, inspect the default routing table using: ```bash theme={null} ip route ``` The output indicates the default gateway. For example, the default route via `172.25.0.1` on interface `eth1` is used for external connectivity. ```bash theme={null} controlplane ~ ➜ ip route default via 172.25.0.1 dev eth1 10.244.0.0/24 dev cni0 proto kernel scope link src 10.244.0.1 172.25.0.0/24 via 10.244.1.0 dev flannel.1 onlink 172.25.0.0/24 dev eth1 proto kernel scope link src 172.25.0.42 192.5.114.0/24 dev eth0 proto kernel scope link src 192.5.114.3 controlplane ~ ➜ ``` Thus, the default gateway is `172.25.0.1`. *** ## 10. On Which Port Is the Kube Scheduler Listening? To determine the port on which the Kube Scheduler is active, use the netstat command with filtering options: ```bash theme={null} netstat -np1 | grep -i scheduler ``` The output shows that the scheduler is listening on port `10259` on localhost. ```bash theme={null} tcp 0 0 127.0.0.1:10259 0.0.0.0:* LISTEN 3281/kube-scheduler ``` *** ## 11. Which ETCD Port Sees More Client Connections? ETCD typically listens on multiple ports, such as `2379` (client communication) and `2380` (peer communication). To inspect ETCD-related sockets, run: ```bash theme={null} netstat -npl | grep -i etcd ``` A sample output could be: ```bash theme={null} 0.0.0.0:2379 LISTEN 3318/etcd 0.0.0.0:2380 LISTEN 3318/etcd 0.0.0.0:12381 LISTEN 3318/etcd 127.0.0.1:12381 LISTEN 3318/etcd ``` To count established connections for each port, use the following commands: ```bash theme={null} netstat -npa | grep -i etcd | grep -i 2379 | wc -l netstat -npa | grep -i etcd | grep -i 2380 | wc -l ``` Typically, port `2379` will show significantly more client connections compared to port `2380`, which is reserved for peer-to-peer communication among ETCD members. *** This concludes the lab. Each step illustrated above demonstrates how to gather network and runtime configuration details within your Kubernetes cluster environment. For further reading on Kubernetes networking and node configuration, please visit the [Kubernetes Documentation](https://kubernetes.io/docs/).