Networking - Networking Basics - Discussion

Everybody is confused because desimal binary conversation, here is the way to better understand this: subnet is all 1s but the last 6 digits determines hosts. You cant do anything for the fist 24 bits because they are fixed (255.255.255) you have play with the first 2 bits of the last octet, they can be:

00xxxxxx
01xxxxxx
10xxxxxx
11xxxxxx

In other word, you can create 4 different networks out of these bits, now convert them to decimal:
The first one's max value will be 63 (if all x were 1) which is not even close to 188.

Second posibility or network can be max 127 not close to 188.

Third one is good, it can be max 191 (don't forget you can't change the 0 on the second digit from left, it is belong to network portion not host, so max=1011111y. Here you cannot make y=1 because when it is 1 with other bits, it becomes network address.

11xxxxxx's min address is 192 so it will never contain 188 although other bits were 0.

256-192 = 64 so increment by 64.

Networ - Broadcast
64 - 127
128 - 191 > so the usable host address range is 127 - 190 (answer is A).
192 - 255.

The answer is right they said "usable" ip address, so the network is 192.168.168.128 to .191, 128 is network address and 191 is broadcast address.

The correct answer will be 192.168.168.128 - 191.

Not getting the solution, please explain me in detail.

128 is called a network address and 191 is called broadcast address.

Thanks it is easy to understand.

@Shyamnarayan.

Your answer is perfect with the simple solution.

Hi, @All.

Subtract 192 from 256 = 64,

Means, the subnetting has been done by dividing into four parts, 64 * 4 = 256.
Now see the option.
64 * 2 = 128,
And 64 * 3 = 192.

So IP add should be in between.

192.168.168.129 to 192.168.168.191.

64 - 2 = 62 then b is the answer.

@Ravi Sankar.

Why you call 64 as magic number and why not 192? Please help me.