UNIX allows file access based on __________.

A.
GID or UID and ACLs.

B.
GID or UID and UNIX permissions.

C.
NT ACLs and SID.

D.
NT ACLs and UNIX permissions.

Explanation:
* Unix-like operating systems identify users within the kernel by an unsigned integer value called a
user identifier, often abbreviated to UID or User ID. The range of UID values varies amongst
different systems; at the very least, a UID represents a 15-bit integer, ranging between 0 and
The UID value references users in the /etc/passwd file. Shadow password files and Network
Information Service also refer to numeric UIDs. The user identifier has become a necessary
component of Unix file systems and processes.
* In POSIX-compliant environments the command-line command id gives the user’s user identifier
number as well as more information on the user account like the user name, primary user group
and group identifier (GID).

* Files and directories are owned by a user. The owner determines the file’s owner class. Distinct
permissions apply to the owner.
Files and directories are assigned a group, which define the file’s group class. Distinct permissions
apply to members of the file’s group members. The owner may be a member of the file’s group.
Users who are not the owner, nor a member of the group, comprise a file’s others class. Distinct
permissions apply to others.
The effective permissions are determined based on the user’s class. For example, the user who is
the owner of the file will have the permissions given to the owner class regardless of the
permissions assigned to the group class or others class.