这是图片被联通 CDN 了吗

今天打开网站发现部分图片不显示，用 360 浏览器的“审查元素”功能发现不能显示的图片前被加了“ http://120.52.72.70/”前缀，比如：
原本图片地址是： http://aliyun.youhuima.cc/c3pr90ntcsf0/wp-content/uploads/2015/12/500-300x218.jpg ，网页 html 代码查看也是这个地址

但实际是 get 的这个地址： http://120.52.72.70/aliyun.youhuima.cc/c3pr90ntcsf0/wp-content/uploads/2015/12/500-300x218.jpg

网站没有开启 CDN 。查了 120.52.72.70 归属，发现是联通云数据公司，我用的是联通宽带。这是被联通给 CDN 了吗？还是别的原因。

apnic 查询结果：
% APNIC found the following authoritative answer from: whois.apnic.net
% [whois.apnic.net]
% Whois data copyright terms http://www.apnic.net/db/dbcopyright.html
% Information related to '120.52.0.0 - 120.52.255.255'
inetnum: 120.52.0.0 - 120.52.255.255
netname: CU-CDC
descr: CHINA UNICOM CLOUD DATA COMPANY LIMITED
descr: A133, Xidan North Avenue, Xicheng District, Beijing.
admin-c: ZM909-AP
tech-c: ZM909-AP
country: CN
mnt-by: MAINT-CNNIC-AP
mnt-lower: MAINT-CNNIC-AP
mnt-routes: MAINT-CNNIC-AP
mnt-irt: IRT-CNNIC-CN
status: ALLOCATED PORTABLE
changed: hm-changed@apnic.net 20131012
source: APNIC
irt: IRT-CNNIC-CN
address: Beijing, China
e-mail: ipas@cnnic.cn
abuse-mailbox: ipas@cnnic.cn
admin-c: IP50-AP
tech-c: IP50-AP
auth: # Filtered
remarks: Please note that CNNIC is not an ISP and is not
remarks: empowered to investigate complaints of network abuse.
remarks: Please contact the tech-c or admin-c of the network.
mnt-by: MAINT-CNNIC-AP
changed: ipas@cnnic.cn 20110428
source: APNIC
person: Xin Xing
address: A133,Xidan North Avenue, Xicheng District, Beijing
country: CN
phone: +86-18618215599
e-mail: xingxin2@chinaunicom.cn
nic-hdl: ZM909-AP
mnt-by: MAINT-CNNIC-AP
changed: ipas@cnnic.net 20131012
source: APNIC