Fri Apr 04, 2008 8:56 pm
Calculating IP address without calculating binary system, only for SUBNETTING.
All you need to calculate from IP addresses is
1. Network Address?
2. Broadcast Address?
3. Subnet Mask?
4. Total Usable Host?
5. First Usable Host?
6. Last Usable Host?
First of All just keep in mind
/25 for 128.
Now count
/26 for 192 (Difference between /25 and /26 is 128 + 64 )
/27 for 224 (Difference between /26 and /27 is 192 + 32 )
/28 for 240 (Difference between /28 and /27 is 224 + 16 )
/29 for 248 (Difference between /29 and /28 is 240 + 8 )
/30 for 252 (Difference between /30 and /29 is 248 + 4 )
Now let’s, get an example: you have got an IP address from your ISP like 192.168.100.27/25.
What does it mean?? How to find out answers of above question?
Look at the slash ( / ) prefix of the IP address. It is /25 which represent the subnet mask 255.255.255.128. It also means total 128 host number is available in the network.
Network Address and Broadcast Address?
It has total 128 host and you’ve got the IP address 27, now multiply 128 to find in which range you got IP address 27. It is between 0 – 127, so that your Network address is 0 and all we know the last address of the network is broadcast address, so which is 127.
Subnet mask?
As we already defined the subnet mask is 255.255.255.128.
Total Usable Host?
For all network usable host = Total host – 2 (2 goes for network and broadcast address)
First Usable Host?
That is 1, my dear.
Last Usable Host?
126, hope all of you understand why. Cuz when 127 goes for broadcast address so that 126 is the last address which can you put to any node.
That’s ALL
But I think another example will help you all. So giving another example:
Let assume another IP address like 172.16.212.177/27. We need to find out all above information about this IP address block.
Also look at the slash ( / ) prefix here. It is /27 which represent the subnet mask 255.255.255.224. It also means total 32 host number is available in the network.
Network and Broadcast Address?
According to our calculation for /27, total host is 32. Our IP address is 177, now multiply 32 to find in which range you got IP address 177. It’s between 160–191 (I know it is 160 - 192; here I wrote 191 cuz if you include 160 and added more 32 number then it will 191) , so that your network address is 160 and your broadcast address is 191.
Subnet Mask?
It is 255.255.255.224
Total Usable Host?
Calculated, it is 30.
First Usable Host?
It is 161.
Last Usable Host?
190.
Rafiq...