Your company has an Active Directory forest. Not all domain controllers in the forest are
configured as Global Catalog Servers. Your domain structure contains one root domain and
one child domain.
You modify the folder permissions on a file server that is in the child domain. You discover
that some Access Control entries start with S-1-5-21 and that no account name is listed.
You need to list the account names.
What should you do?

A.
Move the RID master role in the child domain to a domain controller that holds the Global
Catalog.

B.
Modify the schema to enable replication of the friendlynames attribute to the Global
Catalog.

C.
Move the RID master role in the child domain to a domain controller that does not hold
the Global Catalog.

D.
Move the infrastructure master role in the child domain to a domain controller that does
not hold the Global Catalog.

Explanation:
http://technet.microsoft.com/en-us/library/cc780850%28v=ws.10%29.aspx
Security identifiers
Security identifiers (SIDs) are numeric values that identify a user or group. For each access
control entry (ACE), there exists a SID that identifies the user or group for whom access is
allowed, denied, or audited. Well-known security identifiers (special identities):
Network (S-1-5-2) Includes all users who are logged on through a network connection.
Access tokens for interactive users do not contain the Network SID.
http://technet.microsoft.com/en-us/library/cc773108%28v=ws.10%29.aspx
Operations master roles Active Directory supports multimaster replication of the directory
data store between all domain controllers (DC) in the domain, so all domain controllers in a
domain are essentially peers. However, some changes are impractical to perform in using
multimaster replication, so, for each of these types of changes, one domain controller, called
the operations master, accepts requests for such changes.
In every forest, there are at least five operations master roles that are assigned to one or
more domain controllers. Forest-wide operations master roles must appear only once in
every forest. Domain-wide operations master roles must appear once in every domain in the
forest.
Domain-wide operations master roles
Every domain in the forest must have the following roles:
Relative ID (RID) master
Primary domain controller (PDC) emulator master
Infrastructure master
These roles must be unique in each domain. This means that each domain in the forest can
have only one RID master, PDC emulator master, and infrastructure master.
…
Infrastructure master
At any time, there can be only one domain controller acting as the infrastructure master in
each domain.
The infrastructure master is responsible for updating references from objects in its domain to
objects in other domains. The infrastructure master compares its data with that of a global
catalog. Global catalogs receive regular updates for objects in all domains through
replication, so the global catalog data will always be up to date. If the infrastructure master
finds data that is out of date, it requests the updated data from a global catalog. The
infrastructure master then replicates that updated data to the other domain controllers in the
domain.
Important
Unless there is only one domain controller in the domain, the infrastructure master role
should not be assigned to the domain controller that is hosting the global catalog. If the
infrastructure master and global catalog are on the same domain controller, the

infrastructure master will not function. The infrastructure master will never find data that is
out of date, so it will never replicate any changes to the other domain controllers in the
domain.
In the case where all of the domain controllers in a domain are also hosting the global
catalog, all of the domain controllers will have the current data and it does not matter which
domain controller holds the infrastructure master role.
The infrastructure master is also responsible for updating the group-to-user references
whenever the members of groups are renamed or changed. When you rename or move a
member of a group (and that member resides in a different domain from the group), the
group may temporarily appear not to contain that member.
The infrastructure master of the group’s domain is responsible for updating the group so it
knows the new name or location of the member. This prevents the loss of group
memberships associated with a user account when the user account is renamed or moved.
The infrastructure master distributes the update via multimaster replication.
There is no compromise to security during the time between the member rename and the
group update. Only an administrator looking at that particular group membership would
notice the temporary inconsistency.