按照您这章的步骤，我回顾了一下，启动ETCD集群，测试集群状态

[root@node-1 ~]# ETCDCTL_API=3 etcdctl member list \
>   --endpoints=https://127.0.0.1:2379 \
>   --cacert=/etc/etcd/ca.pem \
>   --cert=/etc/etcd/kubernetes.pem \
>   --key=/etc/etcd/kubernetes-key.pem
17699d00ab051ce0, started, node-3, https://172.16.1.23:2380, https://172.16.1.23:2379, false
30f1ad6e6bfae91e, started, node-1, https://172.16.1.21:2380, https://172.16.1.21:2379, false
bf0f7b27e53ff62b, started, node-2, https://172.16.1.22:2380, https://172.16.1.22:2379, false
[root@node-1 ~]# netstat -lntup|grep 2379
tcp        0      0 172.16.1.21:2379        0.0.0.0:*               LISTEN      1874/etcd           
tcp        0      0 127.0.0.1:2379          0.0.0.0:*               LISTEN      1874/etcd   
[root@node-1 ~]# netstat -lntup|grep 2380
tcp        0      0 172.16.1.21:2380        0.0.0.0:*               LISTEN      1874/etcd   

然而我发现，下述操作报错了

[root@node-1 ~]# journalctl -f -u etcd
Dec 02 01:40:49 node-1 etcd[1874]: 
rejected connection from "127.0.0.1:52376" 
(error "tls: first record does not look like a TLS handshake", ServerName "")

[root@node-1 ~]# systemctl status etcd -l
Dec 02 01:48:09 node-1 etcd[1874]: 
rejected connection from "172.16.1.23:41544"
 (error "tls: first record does not look like a TLS handshake", ServerName "")
Dec 02 02:25:20 node-1 etcd[1874]: 
rejected connection from "127.0.0.1:55064"
 (error "tls: first record does not look like a TLS handshake", ServerName "")

问题一:172.16.1.23并没有41544这个端口，为啥还要访问？这个功能是干啥的？
问题二:这个异常如何解决？

 (error "tls: first record does not look like a TLS handshake", ServerName "")

我搜了一下课程回答内容和其他网站，发现有证书问题，但并不是我的异常描述。

然后我模糊的测试了一下ETCDCTL命令
直接执行get依然报错，

[root@node-1 ~]# etcdctl get /test 
{"level":"warn","ts":"2022-12-02T02:26:23.574+0800","caller":"clientv3/retry_interceptor.go:62","msg":"retrying of unary invoker failed","target":"endpoint://client-5cabab7f-c9d1-4aed-b3cf-4710af6cacf8/127.0.0.1:2379","attempt":0,"error":
"rpc error: code = DeadlineExceeded desc = latest balancer error: 
all SubConns are in TransientFailure, latest connection error: connection closed"}

问题三:下述异常和问题三有没有关联？
但是，当我手工加入证书路径之后，就能正常的get和set了

[root@node-1 ~]# etcdctl --cacert=/etc/etcd/ca.pem --cert=/etc/etcd/kubernetes.pem --key=/etc/etcd/kubernetes-key.pem put /test zhangsan
OK
[root@node-1 ~]# etcdctl --cacert=/etc/etcd/ca.pem --cert=/etc/etcd/kubernetes.pem --key=/etc/etcd/kubernetes-key.pem get /test
/test
zhangsan
[root@node-1 ~]# etcdctl member list --write-out=table --cacert=/etc/etcd/ca.pem --cert=/etc/etcd/kubernetes.pem --key=/etc/etcd/kubernetes-key.pem
+------------------+---------+--------+--------------------------+--------------------------+------------+
|        ID        | STATUS  |  NAME  |        PEER ADDRS        |       CLIENT ADDRS       | IS LEARNER |
+------------------+---------+--------+--------------------------+--------------------------+------------+
| 17699d00ab051ce0 | started | node-3 | https://172.16.1.23:2380 | https://172.16.1.23:2379 |      false |
| 30f1ad6e6bfae91e | started | node-1 | https://172.16.1.21:2380 | https://172.16.1.21:2379 |      false |
| bf0f7b27e53ff62b | started | node-2 | https://172.16.1.22:2380 | https://172.16.1.22:2379 |      false |
+------------------+---------+--------+--------------------------+--------------------------+------------+

问题四:
下述异常和问题三中不手工加证书执行时出现异常，对后续集群和课程有没有影响？

 (error "tls: first record does not look like a TLS handshake", ServerName "")

谢谢老师。