Customer Self-Service Portal

Website monitoring

Hello!. I am testing the free version of the service offered by Site24x7. Yesterday 6 "Down" states were reported on my site but in the access logs on my server all Site24x7 accesses appear with http code 200. I expected to find http 5xx codes. How does Site24x7 determine that a website is down?, or When does Site24x7 consider that a website is down? Thanks in advance