some questions on partII instruction...

[Newman Huang]

1."..have their site available four 9's..."(payment sys provided by Transmaster)
what is the meaning of 'four 9's'?
2. the FBN CEO answered the concurrent users in peaktime, and said that the new system would support 20 agents and 600 customers mostly. does it mean support over 600 concurrent requests or 600 online users?

[Ben Spivey]

I may be mistaken, but I think that "four nines" means 99.99% guaranteed uptime.

[Sourav Gupta]

For 2: my interpretation was to support 600 concurrent web requests at peak.

[Newman Huang]

thanks ben and sourav.