DOS stands for Denial of service. It is defined as a nefarious person or group taking steps to flood the server with requests in a goal to overload it.  When Wager web Sportsbook (SBA Rating A) was down the other night, this is exactly the reason why. I spoke with my contact at the company and she assured me this issue has been addressed and will not happen again.

As it turns out other sportsbooks (like Bookmaker, SBA Rating C-) were also under DOS attack at the same time. Their sites are all working now.