I installed CIS v10.0.0.6092 and configured it to the Proactive setting, I followed the same rules as posted previously from Chiracs walk through. However in the Blocked Applications window I can see the number 1 and when I check it tells me it is the Windows Operating System. When I check the Firewall Application Rules for WOS it states Custom - Allow all incoming and outgoing requests. I am not sure how to understand this, can someone tell me what the correct rule for the Windows Operating System should be?. My version of Windows is Windows 7 64bit if this helps.
That rule wouldn’t normally be there unless you choose to unblock WOS from the blocked applications list. You should remove that rule as it is not needed. Also you can check the firewall event logs to see why it was blocked, which most likely was blocked because of the firewall blocking a gratuitous ARP request.
Thanks for the reply. Earlier today before you replied I did another search here on this topic and came across a post about a similar problem someone had, the cause being an unreachable ICMP request. Some hours daily I use a VPN and the rest of the time not. I think this had do do with the blocking in my case due to switching between my normal DNS settings and the VPN DNS settings. The search reply set the following rule which resolved it for him/her. Using Proactive set up as I am. “Block ICMPv4 Out from MAC Any to MAC Any where ICMP message is unreachable”. I have set this in my application rules for WOS and deleted the one mentioned in my OP. I will see how it reacts over the next day or two and hopefully it has been resolved.