Hi, unfortunately, there is not much detail to go on. My first guess is that the server is already monitored under a different name or by FQDN etc etc.
I would need to know a lot of things like; Is the ESX part of vcenter or is it stand alone? What version of Balance e.g. 220.127.116.11 ? What OS and version is the Server e.g. RedHat 6.1?
Balance identifies the VM's based off the UUID. It is the unique identifier similar to a mac address that prevents balance from mistakenly merging statistics of different servers. Is this server from a template? if so, was the SID regen?
Please see some suggestions that may help you;
1) Make sure the server is not already being monitored. balanced will prevent you from adding the same VM twice.
Rediscover your vcenter in Balance
2) Log into Balance web GUI as support | netapp
navigate to the Admin--> advanced --. diagnostics menu
select network tools.
Select the Ping option and enter the IP address for the server that is failing.
this will send a ping request from the Balance "linux" appliance.
3) Check the other network settings -- see the "nslookup" option under the diagnostic tools
Make sure you can Nslookup the IP->Fqdn-> and host name (all 3) and that they "ALL" resolve to the proper server.
4) Verify server in the same network- Domain - vlan etc.
5) is the Domain specified under the admin--> Configuration --> network --> Domain search address? e.g netapp.com mylab.org (select apply/update)
** multiple domains can be specified separated by a space.