Unable to backup any VM on VMWare - VMware_VDDK : NfcNewAuthdConnectionEx: Failed to connect to peer

Running ABR 11.5 on a Windows Server 2008 R2 which is the vCenter VM of our VMWare 4.1.
Anytime I want to Backup a VM I get : VMware_VDDK: [NFC ERROR] NfcNewAuthdConnectionEx: Failed to connect to peer. Error: Host address lookup for server iav-esx1 failed: No address associated with hostname
IAV-ESX1 is one of our VMWare Host.
AcronisESXAppliance is running as a VM.
It is just like AcronisESXAppliance couldn't reach our domain.
Is it possible to enter in command prompt of AcronisESXAppliance to specify the iav-esx1 IP in the /etc/hosts ?

Thanks for your answer.

Regards

LT