MadeEasy Workbook: Computer Networks - Subnetting

Question

Consider the following IP address with corresponding subnet mask:

IP add: 172.60.50.2

Subnet mask: 255.255.224.0

What is the range of assignable IP addresses on the subnet on which the host belongs:

a) 172.60.30.0 - 172.60.63.255

b)172.60.32.1 - 172.60.63.254

c)172.60.32.1  -172.60.64.255

d)172.60.32.0 - 172.60.127.254

Comments

Bt the first and the last address isn't assignable.The 1st address denotes the network address and the last address is the broadcast address.

---

Oh yeah, fair enough. I forgot about that. It should be 172.60.32.1, the first assignable address.

Thank you for correcting.

---

Logically if we see the question asked assignable IP address.

As we cannot assign X.X.X.0(N/W address) and X.X.X.255(DBA), the remaining option is 'B' :).

Answer 1

Given subnet Mask :- 255.255.224.0 = 1111 1111 . 11111111 . 1110 0000 . 0000 0000

host bits = zero bits in Subnet Mask represent HOST bits ===> no.of host bits = 13

 

if you want Network IP address:- put all zeros in host bits in the given ip.

Given IP Address = 172.60.50.2 = 172.60.0010 0000 . 0000 0000 = 172.60.32.0

 

if you want first host address:- put all zeros in host bits in the given ip except LSB, make LSB as 1

Given IP Address = 172.60.50.2 = 172.60.0010 0000 . 0000 0001 = 172.60.32.1

 

if you want last host address:- put all ones in host bits in the given ip except LSB, make LSB as 0

Given IP Address = 172.60.50.2 = 172.60.0011 1111 . 1111 1110 = 172.60.63.254

 

if you want Broadcast address of this network :- put all ones in host bits in the given ip.

Given IP Address = 172.60.50.2 = 172.60.0011 1111 . 1111 1111 = 172.60.63.255

Comments

@Shaik Masthan 

I guess you need to modify the last line.. The last host address which can't be an assignable IP address...

---

@the_bob

Thanks for the correction.

it's a typing mistake ( it occurred due to copy and paste), i will update it.

Answer 2

Yes.. Answer is option B.

Add subnet mask + ip address... You will get subnet id to which this ip belongs to.

Answer 3

Ans  is B