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Quick help needed on Broadcast adress calculation

M

Majesty

Senior member
Hello,

I need to calculate the broadcast adresse from the following IP: 195.3.4.136 with the following mask 255.255.255.22.

Thank you
 


<< 255.255.255.22 >>


Majesty, are you sure you have that mask right? Normally the octets used in a mask are one of the following:

0 128 192 224 240 248 252 or 255
 
Sorry if this is off-topic but where can I learn more about TCP/IP beside reading a 500 page book?
 
Captain_Rob,

I just looked it up, you're right (as always). That might explain why the calculator comes up with some strange results when using lower numbers in the fourth octet of the IP address.

Russ, NCNE
 
Actually, you are right. The right number is &quot;224&quot;.

So, how do I proceed to get the BroadCast adress ?
 
You could &quot;proceed&quot; to the site I linked above. The broadcast address is 195.3.4.159

Russ, NCNE
 
You do it manually by writing out the addresses in binary. Here's how

195.3.4.136 = 11000011.00000011.00000100.10001000
255.255.255.224 = 11111111.11111111.11111111.11100000

You &quot;AND&quot; them to get the network address which is:

195.3.4.128 = 11000011.00000011.00000100.10000000

the broadcast will be the network address with all 1's at the end of the last octet (in this case the last 5 digits since you borrowed the first three of the last octet for the subnet) so it's:

11000011.00000011.00000100.10011111 which is
195.3.4.159 in decimal. Remember, the first three digits, 100, of the last octet are part of the network identifier, the broadcast is the network identifier plus all 1's at the end.

My explanation probably sux but that's how you do it 😀
 
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