Which type of network masking is used when Cisco IOS access control lists are configured?
A.
extended subnet masking
B.
standard subnet masking
C.
priority masking
D.
wildcard masking
Explanation:
Masks are used with IP addresses in IP ACLs to specify what should be permitted and denied. Masks
in order to configure IP addresses on interfaces start with 255 and have the large values on the left
side, for example, IP address 209.165.202.129 with a 255.255.255.224 mask. Masks for IP ACLs are
the reverse, for example, mask 0.0.0.255. This is sometimes called an inverse mask or a wildcard
mask. When the value of the mask is broken down into binary (0s and 1s), the results determine
which address bits are to be considered in processing the traffic. A 0 indicates that the address bits
must be considered (exact match); a 1 in the mask is a “don’t care”.
http://www.cisco.com/c/en/us/support/docs/security/ios-firewall/23602-
confaccesslists.html