Which one of the following is the subnet mask equivalent of

Which one of the following is the subnet mask equivalent of /17?

A. 255.255.255.192

B. 255.255.0.0

C. 255.255.1.0

D. 255.255.128.0

E. 255.255.255.128

Solution

D is correct. The 255.255.128.0 subnet mask is the equivalent of /17.

A, B, C, and E are incorrect. A is not correct because the 255.255.255.192 subnet mask is the equivalent of /26. B is not correct because the 255.255.0.0 subnet mask is the equivalent of /16. C is not correct because the 255.255.1.0 is not a valid subnet mask. E is not correct because the 255.255.255.128 subnet mask is the equivalent of /25.