4 ms·99.999% uptime == 0.001% downtime 0.001% is a factor of 0.00001, not 0.001. Remember, % means 1/100th.by DougWebb 14y ago99.999% uptime == 0.001% downtime 0.001% is a factor of 0.00001, not 0.001. Remember, % means 1/100th.