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Typically if an IP address ends in 255, that will be a broadcast IP.

This is true for a /24 network. But in a /17 network for example, can an IP address for a computer end in 255, or will that always be a broadcast IP address?

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    Yes and no. Yes, if the IP address ending in .255 is not the highest IP in the subnet IP range. No if the IP address ending in .255 is the highest IP address in the subnet IP range. – fpmurphy Nov 28 '17 at 2:54
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Yes, an IPv4 address can end in 255 without being a broadcast address. For it to be a broadcast address, all bits in the host part need to be ones. In your example, the 32-17 = 15 rightmost bits need to be all ones, not only the rightmost eight. For example, 10.0.0.255 in a 10.0.0.0/17 network is not a broadcast address, since the netmask is 255.255.128.0. The broadcast address in this case would be 10.0.127.255.

  • Well, the broadcast address in your example still ends with .255. – Matthias Nov 14 '18 at 14:01
  • @Matthias So? I didn't say the broadcast address doesn't end in 255, I just answered the question by giving an example of an IP address ending in 255 that is not a broadcast address. By the way, the opposite is also true: an address does not need to end in 255 and still be a broadcast address. For example 10.0.0.15 is the broadcast address in the 10.0.0.0/28 subnet. – Johan Myréen Nov 14 '18 at 15:08

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