Are there any risks besides downtimes, if there is only a single domain controller for a small company?
I did some research and everyone recommends at least two domain controllers, but I can't find a real reason why it is so important to have more than one.
Downtimes are no real argument. What is earned, if the second server will allow users to connect to the domain, but the main server hosting files and Exchange is down. The users will not be able to work anyway. This may be interessting if you have more than one Exchange server with DAG, cluster, etc. but not if everything else is not redundant.
On the contrary, it seems to me that a second domain controller will make restore procedures more complicated, because you have to seize FSMO roles, use system state restores, replicate data, etc., while a single domain controller would allow to simply restore a full system backup, created with a backup software that allows creation of online images, because I don't have to care about consistency between two domain controllers.
Can anyone provide me with real risks that could arise from a single domain controller? I won't be able to convince my boss to buy a second server only be telling him "everyone recommends a second domain controller". He will ask the same question as I did: " What are the risks, if we don't have one?"