1.问题

kubeadm搭建集群的时候，执行kubeadm join 192.168.56.100:6443 --token 8idl4o.tnmbohz9gwb690jg --discovery-token-ca-cert-hash sha256:b36a2767690655f3e4b980aedded614232fb0c3694a2330b37985ef78c6b7774 命令时报如下错误：

error execution phase preflight: couldn't validate the identity of the API Server: Get https://192.168.56.100:6443/api/v1/namespaces/kube-public/configmaps/cluster-info?timeout=10s: dial tcp 192.168.56.100:6443: connect: protocol not available

2.可能原因及解决方案（有可能具体哪步操作不清楚）

可能的原因： 之前错误操作，

systemctl stop NetworkManager--临时关闭

systemctl disable NetworkManager --永久关闭网络管理命令

又重新做了如下操作：

systemctl start NetworkManager

systemctl start network.service --开启网络服务