Followed official guide to install Kubernetes cluster with kubeadm on Vagrant.

https://kubernetes.io/docs/getting-started-guides/kubeadm/

• master
• node1
• node2

Master

# kubeadm init --apiserver-advertise-address=192.168.33.200

# sudo cp /etc/kubernetes/admin.conf $HOME/
# sudo chown $(id -u):$(id -g) $HOME/admin.conf
# export KUBECONFIG=$HOME/admin.conf

# wget https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
# kubectl apply -f kube-flannel.yaml

Node1 and Node2

# kubeadm join --token <token> 192.168.33.200:6443
...
[kubeconfig] Wrote KubeConfig file to disk: "/etc/kubernetes/kubelet.conf"

Node join complete:
* Certificate signing request sent to master and response
  received.
* Kubelet informed of new secure connection details.

Run 'kubectl get nodes' on the master to see this machine join.

Until now all success.

But when check kubectl get nodes on master host, retunes only one node:

# kubectl get nodes
NAME                    STATUS    AGE       VERSION
localhost.localdomain   Ready     25m       v1.6.4

Sometimes, it retunes:

# kubectl get nodes
Unable to connect to the server: net/http: TLS handshake timeout

Edit

Add hostname to all the hosts.

Then check kubectl get nodes again from master:

[root@master ~]# kubectl get nodes
NAME                    STATUS    AGE       VERSION
localhost.localdomain   Ready     4h        v1.6.4
master                  Ready     12m       v1.6.4

Just added a new current host name.