<prompt> Which of the following is a valid Subnet Mask?  <response>: The following are examples of valid subnet masks:- 255.255.255.0 CIDR notation 24- 255.255.0.0 CIDR notation 16- 255.0.0.0 CIDR notation 8In general, a valid subnet mask is a 32-bit number with a contiguous sequence of 1s followed by a contiguous sequence of 0s. The number of 1s represents the network portion of the IP address, and the number of 0s represents the host portion of the IP address. 