How many bits are assigned to each permission control for a file or folder?

How many bits are assigned to each permission control for a file or folder?

• A. 1-Bit
• B. 3-Bits
• C. 9-Bits
• D. 8-Bits

Answer: (D)

Permissions are stored as a bitmask, where each flag is a bit that can be on or off. A single permission control for a file or folder is typically encoded in a byte, which is 8 bits. That gives 256 possible flag combinations, enough to represent a practical set of rights and makes bitwise checks fast and simple. If you think about other options: one bit would only show on or off for a single right, which isn’t enough for a useful permission set. Three bits cover only three flags, which is also too limited. Nine bits correspond to the full set of read/write/execute rights across user, group, and others in Unix-like systems, which is a different scope (the entire permission triplet rather than a single control). So eight bits per permission control is the standard encoding.

Permissions are stored as a bitmask, where each flag is a bit that can be on or off. A single permission control for a file or folder is typically encoded in a byte, which is 8 bits. That gives 256 possible flag combinations, enough to represent a practical set of rights and makes bitwise checks fast and simple.

If you think about other options: one bit would only show on or off for a single right, which isn’t enough for a useful permission set. Three bits cover only three flags, which is also too limited. Nine bits correspond to the full set of read/write/execute rights across user, group, and others in Unix-like systems, which is a different scope (the entire permission triplet rather than a single control). So eight bits per permission control is the standard encoding.