Backup & Recovery over the internet- Some help please?

Hi...

We are in the process of rolling out a cloud based backup solution, we are using netbackup 7.5. I have tested LAN backups and it works great...

I need some advice or best methods to connect our clients that will be coming in over the internet...

At the moment, I install the netbackup agent on the client server and enter the master server name. Do I HAVE to add a hosts file entry to see the master server over the internet ? is this the correct method? 

Our clients use various carriers and broadband services, some will also connect with point to point links...I would like the optimal WAN method for multiple carriers that would also not affect the production server when backing up...(dual nics?)

Please advise?