Alibaba Cloud ECS provides standard intranet NTP servers, which you can access from your instances. We also provide external NTP services for instances that need the Internet access.

Intranet and Internet NTP servers

To counterbalance the leap seconds in our world, ECS provides free of charge, highly accurate, and reliable NTP service for both classic network- and VPC-Connected instances. Among the NTP servers, the ntp.cloud.aliyuncs.com achieves nearly zero difference of atomic reference by synchronizing with satellite services. See the following table for the NTP servers provided by Alibaba Cloud ECS.

Classic network intranet VPC intranet Internet
ntp.cloud.aliyuncs.com ntp1.aliyun.com
ntp1.cloud.aliyuncs.com ntp7.cloud.aliyuncs.com ntp2.aliyun.com
ntp2.cloud.aliyuncs.com ntp8.cloud.aliyuncs.com ntp3.aliyun.com
ntp3.cloud.aliyuncs.com ntp9.cloud.aliyuncs.com ntp4.aliyun.com
ntp4.cloud.aliyuncs.com ntp10.cloud.aliyuncs.com ntp5.aliyun.com
ntp5.cloud.aliyuncs.com ntp11.cloud.aliyuncs.com ntp6.aliyun.com
ntp6.cloud.aliyuncs.com ntp12.cloud.aliyuncs.com ntp7.aliyun.com

Other public services of Alibaba Cloud ECS

See the following list for some public services provided by Alibaba Cloud ECS.

Public service Description
Public DNS: 223.5.5.5 / 223.6.6.6 Domain name: http://www.alidns.com
Open source images: http://mirrors.aliyun.com Update frequency: The image files are updated at everyday 02:00−04:00 (UTC+8:00), including a lot of Linux distributions and open source applications.