Networking - Security - Discussion

Discussion :: Security - Security (Q.No.4)

4. 

You need to create an access list that will prevent hosts in the network range of 192.168.160.0 to 192.168.191.0. Which of the following lists will you use?

[A]. access-list 10 deny 192.168.160.0 255.255.224.0
[B]. access-list 10 deny 192.168.160.0 0.0.191.255
[C]. access-list 10 deny 192.168.160.0 0.0.31.255
[D]. access-list 10 deny 192.168.0.0 0.0.31.255

Answer: Option C

Explanation:

The range of 192.168.160.0 to 192.168.191.0 is a block size of 32. The network address is 192.168.160.0 and the mask would be 255.255.224.0, which for an access list must be a wildcard format of 0.0.31.255. The 31 is used for a block size of 32. The wildcard is always one less than the block size.

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