Sorry, could you give a little more detail to help us answer your question ?
I have some machines in the EPO console that when I try to use the ping button appears a message "failed do determine host ip address"...
how epo resolve the names? DNS, WINS...
Firstly, are you sure these machines (a) have an agent installed and (b) are communicating to this ePO server ? (Check the last communication time and the machine properties in the ePO directory).
It's possible to have machines listed in the directory that are not actually connected. For the ping to work you must have an agent installed on the remote machine.
I find that EPO does not use DNS to find machines. It only uses the last reported IP address that it has in its database. If a machine has changed it's IP the Console can not reach out it, you much wait for the client to check in with it's new IP.
The ping option in the EPO GUI does not do a DNS lookup it simply uses the last reported IP. If the machine is "unmanaged" then no IP address will be registered for that machine and you won't be able to ping it. Also if the IP address has changed (DHCP) and the correct IP address has not been reported back to ePO then the ping will not work.
Agent wakeup calls and agent pushes however do a DNS lookup on the system name.