We all plan for the best and prepare for the worst.
All your connections will be restored provided the data does exist where the DNP databases believe it to be.
To take it further.
You should proactively ensure you do not ever need your backup solution. A minimum of RAID 1 configuration for your hard drives on all servers.
Backup all user data to an offsite location. For speed of recovery I would recommend not being at your home or office. This is a good location for a replication of the backup back but if it comes time to restore it, it may take ages to get back to the server(s).
The above goes as well for all database data. Use a program or vendor's software that will allow such backups.
In my case my customer's number one priority is email so I have real time backup for their email and a secondary mail server hosted outside of datacenter where my primary mail server is.
Depending on your situation you may even consider virtualization for all your servers if you are really concerned about recovery (quickly). A VHD can be backed up in its entirety and restored in a matter of minutes if necessary.
If you are hosting publicly I also recommend a bulletproof policy that basically states that although you provide a service and make a best effort attempt to backup and restore (if necessary) your cutomers data it is imperative that they make/keep backups of their data and hold you harmless in the event that you cannot recover from a catastrophic failure.
Lastly maintain a good insurance policy just in case. Mine is with StateFarm.