Group Policy Objects (GPOs) linked to higher levels in a structure are, by default, passed down or inherited to lower levels in the model. This can be overridden at a lower level in the structure. For example, you might apply a desktop security policy for the organization as a whole but apply a more stringent policy to a specific domain in the organization. You can achieve this by linking a GPO to the lower-level domain.
To prevent the default inheritance behavior, implement a Block Inheritance policy, which prevents higher-level linked GPOs from being applied. You should use this sparingly, however, because it can make troubleshooting difficult, so although this option is available and you should be aware that it is possible, use this option only as necessary when designing your Group Policy.
Blocking inheritance
