Networking - Subnetting - Discussion

Discussion :: Subnetting - Subnetting (Q.No.2)


Which two statements describe the IP address

  1. The subnet address is
  2. The lowest host address in the subnet is
  3. The last valid host address in the subnet is
  4. The broadcast address of the subnet is

[A]. 1 and 3
[B]. 2 and 4
[C]. 1, 2 and 4
[D]. 2, 3 and 4

Answer: Option B


The mask (/23) used with a Class A address means that there are 15 subnet bits and 9 host bits. The block size in the third octet is 2 (256 - 254). So this makes the subnets in the interesting octet 0, 2, 4, 6, etc., all the way to 254. The host is in the 2.0 subnet. The next subnet is 4.0, so the broadcast address for the 2.0 subnet is 3.255. The valid host addresses are 2.1 through 3.254.

Ikechukwu said: (Oct 26, 2013)  
I do not understand how option B is the correct answer. I would have thought that option 1 is the only correct description for the IP address.

Mothebe said: (Mar 10, 2014)  
Why is it class A address? I thought that's a class B address.

Vaishali said: (Jul 13, 2014)  
I thought it is a class B address. How can it be class A address? and how the subnet bits can be 15 in this?

Santhosh said: (Jul 27, 2014)  
The valid host id is from to

And the broadcast add is

Sagar Madgundi said: (Sep 23, 2014)  
Why is it class A address? Why is it not class B address?


IP address consists of network and host portion. For example, /24 notation means that first 24 bits are dedicated to the network portion and they remain the same for all hosts in the network, whereas, the last 8 bits uniquely identify each host in the network.

Classful addressing divides IP addresses into 5 different classes, each with its own predefined address range and subnet mask. On the contrary, classless addressing can set the network boundary practically anywhere, thus breaking the classful limitations.

Classful ----> When a IPaddress remains in its default given Subnet mask..
eg. or or

ClassLess----> When a IPaddress is out of its default given Subnet mask..
eg. or or

Atif said: (Jan 28, 2015)  
Option 2 and 4 is correct.


Magic Number is 2. So Range is:


Sub net is No.2:

The range between second is to

Therefore; is the lowest host address in sub net and Broadcast address

Davit said: (Jun 5, 2015)  
00000000.00000000.0000000|0.00000000 its subnet is

Number 2. IP starts from and range of IP is from 2.1 to 3.254. So broadcast address will be

Vishwajeet Mishra said: (Aug 18, 2015)  
Yes, The answer (2 & 4) is a correct option, because now we are working in CIDR Value of (/23), which means we will work on only those bits which have the both combination's of 0's and 1's. So here this happens on third octat of subnet mask.

CIDR Value = /23. So the subnet in binary is => 11111111.11111111.11111110.00000000.

So if we see the third octat then we will see that here is the combination of 0's and 1's. Now, let's find out the value of 1's in third octat. 2^7= 128.

And the total no. Of hosts in a subnetwork= 2^1=2. So here the subnetwork will be 0, 2, 4, 6, 8 and so on because the block size = 2.

So every subnet will made after the gap of 2. How to find the block size = we have to subtract the octat third from 256.

So here we subtract 256-254= 2. It defines the interval of the subnetwork in a subnetted network.

Vishwajeet said: (Aug 18, 2015)  
Then the possible networks will be to, because this is the one subnet. So if we write then this the another network. That's why we take the IP of and For more explanation see my previous post.

Rohit said: (Feb 3, 2016)  
How come is not a valid address keeping in mind that valid address for hosts range from to

Mainodin said: (Mar 8, 2016)  
Why option 3 is wrong ?

Priyanka said: (Mar 29, 2016)  
Why it is started from Why not from or from please tell.

Priyanka said: (Mar 29, 2016)  
Why option 3 is wrong?

(The last valid host address in the subnet is,

I think option 3 is wrong because is the last. Since in 3rd octet its 3 not 2. Therefore, The last valid host address in the subnet is

Abdulrazig Mohammed said: (Apr 3, 2016)  
What is the broadcast for

Milhem said: (Apr 20, 2016)  
Why option 4 is wrong? Explain me.

Sia said: (May 30, 2016)  
Can anyone know the answer for Abdulrazig Mohammed's question?

Ali said: (Jun 30, 2016)  
After calculating how did we come to know that "the possible networks will be to"?

Teshie said: (Jul 11, 2016)  
I don't understand how this will be the right answer.

Davies said: (Jul 24, 2016)  
Please, what is the broadcast for

Aryan said: (Sep 2, 2016) is the subnet mask for the network right?

Then why not option C is correct?

Arunkumar said: (Dec 26, 2016)  
Option C is correct.

The subnet is for10.16.3.0 because the CIDER value is 23.

Arunkumar said: (Dec 26, 2016)  
Hi @Davies.

The answer :

John said: (Jan 31, 2017)  
Good and enough explanation thanks to all.

Nana said: (Apr 25, 2017)  
Buy I thought the up address is class A. Am I right?

Colly said: (May 19, 2017)  
What is the broadcast for Please, explain me.

Nia said: (Jul 14, 2017)  
I think first address should be instead of

because 2^(32-23) = 2^9,
3 : 0 0 0 0 0 0 1 1,
65 : 0 1 0 0 0 0 0 1.

9 means 1 bit from 3rd octet and rest of them from 4th octet,

0 0 0 0 0 0 1 [0. 0 0 0 0 0 0 0 0] = 2.0,
0 0 0 0 0 0 1[1. 1 1 1 1 1 1 1 1 ] = 3.255.

Shailendra Kumar Yadav said: (Nov 22, 2017)  
The lowest host address in the subnet is

It is incorrect because the lowest host address in the subnet is

Monty said: (Jan 20, 2018)  
Why not option A? Please explain.

Sourav Chettr said: (Jan 25, 2018)  
Why option A is not correct?

Usama said: (Apr 11, 2018)  
B) is the correct answer.

The correct explanation is;

First, understand the question, Describe the IP
let's start from the beginning 11111111.11111111.11111110.00000000/23 which mean we are in the third octet.

How many zeroes we have in the third octet? One so 2^1=2 each network.

Now the answer will be:
First = (to) this is N/W first IP last IP Broadcast

Second= (to) N/W First IP last IP Broadcast

And the question asking IP of which is between the second N/W the first or lowest host in second N/W is and last the 255 is broadcast.

Note: lock to the 23 which mean 8+8+7+0. (11111111+11111111+11111110+00000000) How many Zeros we have in the third octet? One So you need to use this formula to get the IP each N/W 2^(number of zeros) in the octet where we are.

Venkatesh said: (Jul 26, 2018)  
The subnet mask for the mentioned IP address is then option 1 is also correct right.

Thishmi said: (Aug 21, 2018)  
Why subnet mask can't take as in option A?

Gexun said: (Feb 23, 2019)  
Thank you for explaining the answer.

Christian Luora said: (Jul 14, 2020)  
Why is option 1 not correct, is it true to say that a subnet address is the same as a subnet mask?

According to me, it is option 2 and 4.

Anyone, please explain in detail.

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