Providing a dedicated backup network for your backup traffic is a sensible strategy. It isolates backup-specific traffic away from other more common production-based traffic in your data center and can often remove dependencies from the production network.
There are a number of prerequisites to enabling a backup network with Microsoft System Center DPM, for example, the availability of a secondary network interface card (NIC), which can be either a physical NIC (pNIC) or a virtual NIC (vNIC: converged network in Hyper-V).
The name resolution can be done either through DNS or the hosts file, since the backup network may not have a DNS server, and this will ensure that you have network connectivity through the backup NIC for both the DPM server and protected servers.