Networking - Subnetting - Discussion

Please explain why would the two hosts be in different sub nets as they both have the 255.255.255.240 and also wouldn't they belong in the same IP range?. Please explain?.

As AND operation of IP address and Subnet mask gives us the Network address. In this case network address is different with given subnet address.

But when subnet mask (255.255.255.0) is used same network address will obtained and hence both will be on same network.

But looking at the mask address they are both on the same mask address 255.255.255.240, please explain.

The Increment (or) Block size is 16, which means the IP Address range will be 192.168.1.0 to 192.168.15.255 if you can see the IP Addresses 192.168.1.20 & 192.168.1.201 falls in between the IP Address. Hence, the IP Address 192.168.1.20 & 192.168.1.201 having mask 255.255.255.240 can communicate.

Can anyone explain clearly why the Answer shows the Masks are different. Please Help?

The series is as follows:

192.168.1.0, valid host(1 to 14).
192.168.1.16, valid host(17 to 30).
192.168.1.32, valid host.
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192.168.1.192 (193 to 206).
192.168.1.208.
192.168.1.224 ().
192.168.1.240.. hence the given IP address of both host falls in different subnets.

I too am confused as it seems they both have the same subnet mask (x.x.x.240) while i agrees the they are different subnets eg .20 is in subnet .16 and .201 is in subnet .192 they clearly share the same subnet mask x.x.x.240 because it states it in the example and it states in the answer that the hosts have different subnet masks, maybe I am not understanding it correctly.

First, if you have two hosts directly connected, then you need a crossover cable. A straight-through cable won't work.

Second, the hosts have different masks, which puts them in different subnets. The easy solution is just to set both masks to 255.255.255.0 /24.

The .244 in mask means that there are only 4 allowable host bits thus can't afford to make address .201 for right host if all 4 bits where ones.

Please explain why?

We cannot use subnet mask 255.255.255.240 with both IP addresses as this subnet mask will take them in two different subnets(networks).

The binary equivalent of 240 is 11110000. i.e 16 is the increment.

The possible networks are:

192.168.1.0 to 192.168.1.15.
192.168.1.16 to 192.168.1.31------>192.168.1.20 belongs to here.
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192.168.1.192 to 192.168.1.207----->192.168.1.201 belongs here.
192.168.1.208 to 192.168.1.223.
192.168.1.224.

So we can clearly see that if we use subnet mask 255.255.255.240 then communication will not be possible as both will be on separate networks. So we have to use 255.255.255.0 subnet in both so that they belong to same network.