This Jenkins instance appears to be offline

lanxi256

[iyunv@server-test jenkins]# wget http://updates.jenkins.io/update-center.json　　
--2017-09-19 12:36:30--  http://updates.jenkins.io/update-center.json
　　
Resolving updates.jenkins.io... 52.202.51.185
　　
Connecting to updates.jenkins.io|52.202.51.185|:80... connected.
　　
HTTP request sent, awaiting response... 301 Moved Permanently
　　
Location: http://updates.jenkins.io/current/update-center.json [following]
　　
--2017-09-19 12:36:30--  http://updates.jenkins.io/current/update-center.json
　　
Reusing existing connection to updates.jenkins.io:80.
　　
HTTP request sent, awaiting response... 302 Found
　　
Location: http://mirrors.jenkins-ci.org/updates/current/update-center.json [following]
　　
--2017-09-19 12:36:31--  http://mirrors.jenkins-ci.org/updates/current/update-center.json
　　
Resolving mirrors.jenkins-ci.org... 52.202.51.185
　　
Reusing existing connection to updates.jenkins.io:80.
　　
HTTP request sent, awaiting response... 302 Found
　　
Location: http://mirrors.tuna.tsinghua.edu.cn/jenkins/updates/current/update-center.json [following]
　　
--2017-09-19 12:36:31--  http://mirrors.tuna.tsinghua.edu.cn/jenkins/updates/current/update-center.json
　　
Resolving mirrors.tuna.tsinghua.edu.cn... 101.6.6.178, 2402:f000:1:416:101:6:6:177
　　
Connecting to mirrors.tuna.tsinghua.edu.cn|101.6.6.178|:80... connected.
　　
HTTP request sent, awaiting response... 200 OK
　　
Length: 1229441 (1.2M) [application/json]
　　
Saving to: “update-center.json”
　　

　　
100%[=====================================================================================================================================================>] 1,229,441   2.43M/s   in 0.5s
　　

　　
2017-09-19 12:36:32 (2.43 MB/s) - “update-center.json” saved [1229441/1229441]