when booting up my test esx 4.0 machines i could not connect to the esx hosts through the vi client, i could connect to the esx host with putty but running a command like

 

vmware-cmd –l gave me a error like this

vim.fault.HostConnectFault: Failed to acquire session manager while querying for local ticket. (503 Service Unavailable)

after some searching i found out that this had something to do with resolving names.

To connect via vSphere client or to connect to cluster Esx-server must resolve himself (only).

If you have any nameserver in resolv.conf – esx will try to resolve himself via that server regardless of /etc/hosts’s content. If that dns-server is inaccessible or it hasn’t records about esx – you get "503 Service Unavailable" during about 15 min. After that esx will "remember" of /etc/hosts.
Esx makes record about himself in /etc/hosts automatically every booting.
It’s only about connect to esx.

so thank god i made a boot option that it will startup my domain controller after 2 minutes and after 3 minutes my virtualcenter.