@ Dennis

I think the link you have sent is for website uptime ???

I think he needs a tool that tells when internet is down - which i believe it will need to show between which times the internet was down... The tool you have suggested is good as it gives % of (some) popular website availability..

A network usage graphing tool would be useful (monitored at egress and ingress ISP link) and one would need to learn internet usage patterns for the office on a daily basis...

Now unless on that day; people become soo busy that no one visits Facebook or Youtube to look at funny American Idol auditions ---

In which case the usage graph will dip and confused for internet outage