“Respond to all (known and unknown) client computers” setting behaviourhttp://msmvps.com/blogs/richardwu/archive/2009/07/01/respond-to-all-known-and-unknown-client-computers-setting-behaviour.aspxIf you select “Respond to all (known and unknown) client computers”, and check the box “For unknown clients, notify administrator and respond after approval”, the result is: When PXE booting a client, it will wait for you to approveenCommunityServer 2008.5 SP2 (Build: 40407.4157)