In 60 Days – ICND2
Wildcard Masks
Why Wildcard Masks?
• They tell router which bits to match
• Done in binary by router
• You write the code
Must Hit 255
Subnet
255
255
255
192
Wildcard
0
0
0
63
Equals
255
255
255
255
Subnet
255
255
224
0
Wildcard
0
0
31
255
Equals
255
255
255
255
Must Hit 255 #2
Subnet
255
255
254
0
Wildcard
0
0
1
255
Equals
255
255
255
255
Subnet
255
128
0
0
Wildcard
0
127
255
255
Equals
255
255
255
255
Matching
• Match traffic from 172.20.1.0
255.255.224.0
255
255
224
0
0
0
31
255
access-list 1 deny 172.20.1.0 0.0.31.255
Matching
• Match traffic from 192.200.1.0
255.255.225.192
255
255
255
192
0
0
0
63
access-list 1 deny 192.200.1.0 0.0.0.63
Matching
• Match traffic from 10.10.10.0
255.255.255.252
255
255
255
252
• Hosts
10.10.10.1
and 10.10.10.2
0
0
0
3
access-list 1 deny 10.10.10.0 0.0.0.3
End