CDN是否存在

Ping、多地ping、国外ping
https://github.com/wwl012345/CDNCheck
单个域名>python3 cndcheck.py -u domain
多个域名>python3 cndcheck.py -f url.txt
https://www.host-tracker.com/
https://www.webpagetest.org/
https://ping.chinaz.com/
https://dnscheck.pingdom.com/
https://github.com/cisagov/findcdn 
  >findcdn list asu.edu -t 7 --double