Once a proposed outcome has enough FLX staked equal to the SB, the settlement period ends and the Challenge period starts. During this period, any validator can post a Challenge Bond (CB) to dispute the outcome of any settlement by staking to a different outcome. The CB has to be of equal value to the SB.
The security of any data request directly correlates to the duration of its challenge period; the longer the duration, the more robust the challenge can be. This duration is always defined by the Data Request set between a window of 5 minutes and 24 hours. If a data request is more arbitrary or doesn’t have a pool of automated validators actively settling requests, it is expected to have a large challenge period. It is almost important to note that every challenge is, in itself, also challengeable