What does CIDR notation /24 indicate about subnet mask length?

What does CIDR notation /24 indicate about subnet mask length?

• A. 8 bits for network portion
• B. 16 bits for network portion
• C. 32 bits for network portion
• D. 24 bits for network portion

Answer: (D)

CIDR notation shows how many high-order bits of the IPv4 address act as the network prefix. An address is 32 bits in total, so /24 means the first 24 bits are the network portion, leaving 8 bits for hosts. That also corresponds to the subnet mask 255.255.255.0. So the subnet mask length indicated by /24 is 24 bits used for the network portion. The other possibilities would use fewer or all of the bits for the network (for example, /8 would use 8 network bits, /16 would use 16, and /32 would use all 32 bits for the network, leaving no host addresses).

CIDR notation shows how many high-order bits of the IPv4 address act as the network prefix. An address is 32 bits in total, so /24 means the first 24 bits are the network portion, leaving 8 bits for hosts. That also corresponds to the subnet mask 255.255.255.0. So the subnet mask length indicated by /24 is 24 bits used for the network portion. The other possibilities would use fewer or all of the bits for the network (for example, /8 would use 8 network bits, /16 would use 16, and /32 would use all 32 bits for the network, leaving no host addresses).