You've made changes to the Default Domain Security Policy, Default Domain Controller Security Policy, or both, and now want to reset them to their original configuration.
The following command would replace both the Default Domain Security Policy and Default Domain Controller Security Policy. You can specify Domain or DC instead of Both, to only restore one or the other.
> dcgpofix /target:Both
Note that this must be run from a domain controller in the target domain where you want to reset the GPO.
If you've ever made changes to the default GPOs and would like to revert back to the original settings, the dcgpofix utility is your solution. dcgpofix works with a particular version of the schema. If the version it expects to be current is different from what is in Active Directory, it will not restore the GPOs. You can work around this by using the /ignoreschema switch, which will restore the GPO according to the version dcgpofix thinks is current. The only time you might experience this issue is if you install a service pack on a domain controller (dc1) that extends the schema, but have not installed it yet on a second domain controller (dc2). If you try to run dcgpofix from dc2, you will receive the error since a new version of the schema and the dcgpofix utility was installed on dc1.