Our server is 99.9% + reliable, but this is still a possibility.
However, we have a mirror server that acts as a backup to our main server, and it is also has a reliability rating of 99.5% + percent.
So, the chances of both of our servers being down at the same time are very remote.
If both of the servers ever did go down at the same time, any snipes that were scheduled to execute while they were down would not be submitted to eBay. Once the server is up again, the sniper engine will pick up from there, executing scheduled snipes.