I am trying to setup kubernetes on my bare metal cluster using kubeadm. But during initialization kubeadm init i get following error :

[root@server docker]# kubeadm init
[init] using Kubernetes version: v1.11.2
[preflight] running pre-flight checks
        [WARNING Firewalld]: firewalld is active, please ensure ports [6443 10250] are open or your cluster may not function correctly
        [WARNING HTTPProxy]: Connection to "https://192.111.141.4" uses proxy "http://lab:on@192.111.141.15:3122". If that is not intended, adjust your proxy settings
        [WARNING HTTPProxyCIDR]: connection to "10.96.0.0/12" uses proxy "http://lab:on@192.111.141.15:3122". This may lead to malfunctional cluster setup. Make sure that Pod and Services IP ranges specified correctly as exceptions in proxy configuration
I0827 16:33:00.426176   34482 kernel_validator.go:81] Validating kernel version
I0827 16:33:00.426374   34482 kernel_validator.go:96] Validating kernel config
        [WARNING SystemVerification]: docker version is greater than the most recently validated version. Docker version: 18.06.0-ce. Max validated version: 17.03
[preflight/images] Pulling images required for setting up a Kubernetes cluster
[preflight/images] This might take a minute or two, depending on the speed of your internet connection
[preflight/images] You can also perform this action in beforehand using 'kubeadm config images pull'
[kubelet] Writing kubelet environment file with flags to file "/var/lib/kubelet/kubeadm-flags.env"
[kubelet] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[preflight] Activating the kubelet service
[certificates] Generated ca certificate and key.
[certificates] Generated apiserver certificate and key.
[certificates] apiserver serving cert is signed for DNS names [server.test.com kubernetes kubernetes.default kubernetes.default.svc kubernetes.default.svc.cluster.local] and IPs [10.96.0.1 192.111.141.4]
[certificates] Generated apiserver-kubelet-client certificate and key.
[certificates] Generated sa key and public key.
[certificates] Generated front-proxy-ca certificate and key.
[certificates] Generated front-proxy-client certificate and key.
[certificates] Generated etcd/ca certificate and key.
[certificates] Generated etcd/server certificate and key.
[certificates] etcd/server serving cert is signed for DNS names [server.test.com localhost] and IPs [127.0.0.1 ::1]
[certificates] Generated etcd/peer certificate and key.
[certificates] etcd/peer serving cert is signed for DNS names [server.test.com localhost] and IPs [192.111.141.4 127.0.0.1 ::1]
[certificates] Generated etcd/healthcheck-client certificate and key.
[certificates] Generated apiserver-etcd-client certificate and key.
[certificates] valid certificates and keys now exist in "/etc/kubernetes/pki"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/admin.conf"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/kubelet.conf"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/controller-manager.conf"
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/scheduler.conf"
[controlplane] wrote Static Pod manifest for component kube-apiserver to "/etc/kubernetes/manifests/kube-apiserver.yaml"
[controlplane] wrote Static Pod manifest for component kube-controller-manager to "/etc/kubernetes/manifests/kube-controller-manager.yaml"
[controlplane] wrote Static Pod manifest for component kube-scheduler to "/etc/kubernetes/manifests/kube-scheduler.yaml"
[etcd] Wrote Static Pod manifest for a local etcd instance to "/etc/kubernetes/manifests/etcd.yaml"
[init] waiting for the kubelet to boot up the control plane as Static Pods from directory "/etc/kubernetes/manifests"
[init] this might take a minute or longer if the control plane images have to be pulled

                Unfortunately, an error has occurred:
                        timed out waiting for the condition

                This error is likely caused by:
                        - The kubelet is not running
                        - The kubelet is unhealthy due to a misconfiguration of the node in some way (required cgroups disabled)
                        - No internet connection is available so the kubelet cannot pull or find the following control plane images:
                                - k8s.gcr.io/kube-apiserver-amd64:v1.11.2
                                - k8s.gcr.io/kube-controller-manager-amd64:v1.11.2
                                - k8s.gcr.io/kube-scheduler-amd64:v1.11.2
                                - k8s.gcr.io/etcd-amd64:3.2.18
                                - You can check or miligate this in beforehand with "kubeadm config images pull" to make sure the images
                                  are downloaded locally and cached.

                If you are on a systemd-powered system, you can try to troubleshoot the error with the following commands:
                        - 'systemctl status kubelet'
                        - 'journalctl -xeu kubelet'

                Additionally, a control plane component may have crashed or exited when started by the container runtime.
                To troubleshoot, list all containers using your preferred container runtimes CLI, e.g. docker.
                Here is one example how you may list all Kubernetes containers running in docker:
                        - 'docker ps -a | grep kube | grep -v pause'
                        Once you have found the failing container, you can inspect its logs with:
                        - 'docker logs CONTAINERID'
couldn't initialize a Kubernetes cluster

Preflight images are also present on my system but still I get this error. After [init] this might take a minute or longer if the control plane images have to be pulled this statement, kubeadm waits about 5-10 minutes before giving this error. What is cause of this error?