Can I set an IP mask on CISCO 2514?

Q: Our school machine room began to build a campus network, the router is selected CISCO 2514, In the settings, the problem is that on CISCO 2514 if there is no "IP SUBNET-ZERO ", if the ethernet interface mask is used, it cannot be set up. IP address and subnet mask are allocated by mains. It should be correct. I think it is okay if it is not set, isn't it?

A: this is the case. For example, if 168.32.64.0 is divided into four network segments based on 255.255.255.255.192, 168.32.64.0/26,168.32 .64.64/26,168.32 .64.128/26,168.32 .64.192/26. however, the subnet network address of 168.32.64.0/26 is the same as that of 168.32.64.0/24. In addition, the subnet broadcast address of 168.32.64.192/26 is listen, which is the same as the broadcast address of 168.32.64.0/24. that is to say, we cannot tell the difference between the 168.32.64.0/26 network address and the 168.32.64.0/24 network address. In addition, we cannot tell the difference between the broadcast address of 168.32.64.192/26 and the broadcast address of 168.32.64.19, therefore, in IOS by default, the two subnets are not used. If you want to use them, use the command ip subnet-zero.

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