Networking - Networking Basics - Discussion

Thank you @Jitendra.

Where did 156-192 come from?

This is the trick for this one.

The given is 192.168.188.188 with a subnet of 255.255.255.192. This subnet is /26. You should know the value of the increment of each subnet mask. In this case, it's 64.

Since it's in the fourth octet, we can now find the CLOSEST number which can be divided by the increment value. Only below the range of the given IP.

In this case, 128 is the CLOSEST number to the given 188 that CAN BE DIVIDED by the INCREMENT VALUE which is 64.

So we know that the IP will be 192.168.188.188 /26.

Since the increment value is 64 which is also the number of IP addresses, we will just ADD 64 to 128. Which will give us the last IP 192.168.188.192.

So, what do we have now?

First IP: 192.168.188.128 which is the NETWORK ADDRESS.
Last IP: 192.168.188.192 which is the BROADCAST ADDRESS.

These 2 IPs cannot be used.

So the usable IP range will be 192.168.188.129 to 192.168.188.191

Always remember that the first and last IP of the IP range is the Network and Broadcast addresses, respectively. And they are cannot be used.

I hope this will be a clear solution.

Answer (A) is right.

Because valid host means usable ip.
The CIDR is;

Subnet=192.168.168.128
First Usable IP= 192.168.168.129
Last usable IP is= 192.168.168.190
Broadcast IP is= 192.168.168.191.
so, answer is correct.

@Richa.

Where did you get that 191?

As you said n/w add starts from 128 and end to 191 how?

I didn't understand. Can anyone explain me clearly please?

Actually the value given is wrong. the value should be 192.168.168.128

then only we can get the correct value.

192-128=64

so that we can get 64 values.that valid host range value should be between 129 to 191.

i think correct answer is B.

does anybody refuse it....?

Why the value should be between 129 and 191. It should be between 128-191. Also why the broadcast address is 191?

This value is right not wrong.
First of all we need to be the see the address and now.

We take broadcast address 256 then in this we subtract the value of last gourd subnet mask (192). Then we add the same bit of subtracting then we find the 128 also and then we re add the value (64) then we find out the 192 this will be the broadcast address of segment.

Here the subnet mask is 255.255.255.192 means only the last value is changing so subtract it from 255, you will get 64 means out of 255 IP's 64 is already used only 192 IP's are available.

256/4=64 means 0-63, 64-127, 128-191, 192-255 all 4 segments contains 64 IP's, out of which one segment is already used (lets not worry about it).

Now check the IP given which is 192. 168. 168. 188 which falls in the range 128-191 so here the valid host range will be from 129-190 because first one is always network IP, the last one is always the broadcast IP.