Hello everyone.Why do we use a wildcard mask Instead subnet mask?I know that in the wildcard mask; 0 is important and in the subnet mask 1 is important. but I can't understand why we use a wildcard mask?

Hello, I have a question!  I have one switch 2960 and one router. in switch, I have 3 VLANs. VLAN 2, 3, and 4.I want VLAN 2 to connect to VLAN 3 and  VLAN 4, but VLAN 3 and 4 can not connect to VLAN 2. Do I have to use the Access List? How do I write...