Group Policy can map to Sites, Domain and OUs. If group policy is mapped to OU, by default it will apply to any object under it. But within a OU, Domain or Site there are lots of objects. The security, system or application settings requirements covers by group policies not always applies to boarder target groups. Group Policy filtering capabilities allows to further narrow down the group policy target to security groups or individual objects.
There are few different ways we can do the filtering in group policy.
1) Security Filtering
2) WMI Filtering
In this post we are going to look in to Security Filtering. In one of my previous post I already covered WMI filtering. It can be found under https://www.rebeladmin.com/2018/02/group-policy-wmi-filters-nutshell/
Before apply the security filtering, the first thing to make sure is group policy mapped correctly to the Site, Domain or OU. The security group or the objects you going to target should be under correct level where group policy is mapped.
We can use the GMPC or PowerShell cmdlets to add the security filtering to GPO.