Which of the following answers lists the prefix (CIDR) format equivalent of 255.192.0.0?

(A) /10
(B) /11
(C) /12
(D) /13

/10 is the correct answer.

Convert one octet at a time:
The first octet (255) convert to an 8-bit binary 11111111 total 8.
The second octet (192) convert to an 8-bit binary 11000000 total 2.
The third octet (0) convert to an 8-bit binary 00000000 total 0.
The fourth octet (0) convert to an 8-bit binary 00000000 total 0.
The equivalent of 255.192.0.0 is 11111111.11000000.00000000.00000000
The total number of binary 1s (which defines the prefixlength) is 8 + 2 + 0 + 0 = /10.

Binary Mask Octet	Decimal Equivalent	Number of Binary 1s
00000000	0	0
10000000	128	1
11000000	192	2
11100000	224	3
11110000	240	4
11111000	248	5
11111100	252	6
11111110	254	7
11111111	255	8