Backup and Restore Active Directory

Dear All,

it is time to here to know the solution about the back up and restore for active directory 

1.How to do the back up of active directory 

2.does it cover all the object if i will take the back up from symantech product (like users,computer and policies)

3.in case my server is crashed (HDD failure,data lost by attacking virus)

4. can recovery all the data to my new server ( means to new domain controller )

because i am totally new to your products even i never had a experience in backup of active directory 

in my new company they are using symantec netbackup 7.5

Regards

Azad