Lets take a more complicated example. The mask supplied to an access list indicates which bits are significant. If the mask contains a 0 bit, that bit must be checked in the address in question. If the mask contains a 1 bit, that bit is a wildcard and is NOT checked. 248 Bin 00000000.00000000.00000000.11111000 indicates that the upper five bits in the last octet are wildcards and are NOT to be checked.
Lets compute an example now.
209.212.190.4 Dec 209. As specified by the mask, the upper five bits in the last octet are ignored for comparison. So lets do a bit for bit comparison. This indicates there is NOT a match. Even an address such as 209.212.190.44 is allowed.