DNS Resolution

Happens on only some client that's the DNS name resolution fail.
On a first troubleshoointg the ping command pointing the server name fails, but nslookup not and do not fail also the ping with FQDN.

Both the nic configuration and os settings in the "workstation name" label window has the append dns suffix value.

After a long search I found this interesting articles:
http://technet.microsoft.com/en-us/library/cc755882%28v=ws.10%29.aspx

http://blogs.technet.com/b/networking/archive/2009/04/16/dns-client-name-resolution-behavior-in-windows-vista-vs-windows-xp.aspx 

The second one has something that should be the correct resolution:

Modify this registry key 

This registry entry works for both Windows XP and Windows Vista
HKLM\Software\Policies\Microsoft\Windows NT\DNSClient\AppendToMultiLabelName
Type = DWORD
Data:

• 0 (Do not Append Suffix)
• 1 (Append suffix)

Else a Group Policy should be used but only from Windows Vista:

Group Policy location (for Windows Vista only) - (run gpedit.msc):
Computer Configuration -> Administrative Templates -> Network -> DNS Client -> “Allow DNS Suffix Appending to Unqualified Multi-Label Name Queries”