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I'm not too clear on subnetting rules and experienced an error when I tried to assign 148.26.1.176/28 to an interface on my Cisco router. Can someone please explain why it was not allowing me to assign this address to the interface?

I receive an error saying:

Bad mask /28 for address 148.26.1.176

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    I strongly suggest changing your title for something that summarize your question. As is I will not event read the actual question... – JFL Nov 29 '17 at 10:31
  • I also suggest you change the title to something which might make people want to help you. – jonathanjo Nov 29 '17 at 10:39
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    I find it somewhat amusing that the IP address here is exactly the same as the one in the 4,5 year old duplicate. Is this from some bad example somewhere? – ilkkachu Nov 29 '17 at 14:33
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/28 means that you are assigning the last 4 bits to the host part of the address.

176 in binary is 10110000.

The last 4 bits are zero, it means that it is the network address of the subnet.

You can't assign to a device the first address (network address) or the last address (broadcast address) of a subnet.


A little trick:

In this case, the 4 bits for host part, means that you will have 16 address on each subnet.

Then divide 176/16, if the division is exact without decimals then is a network address and can't be used.

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