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  • Tat Luk thinks this is interesting:

nd subtract the regular subnet mask, which in this case would be 255.255.252.0. The result is 0.0.3.255.

From

Cover of Routing and Switching Essentials Companion Guide

Note

Figure is correct but the statement is incorrect, it should be subnet mask 255.255.254.0, wildcard mask is 0.0.1.255