# Subnetting IP Address Class C /25

Hello friends, welcome to Ceflox. On this occasion we will discuss IP Address Subnetting. How does the IP address on each device vary, this is done by subnetting an IP address according to its class. The following is  How to Calculate Subnetting IP Address Class C /25.

### How to Subnetting IP Address Class C /25

• Understanding IP Address and Subnetting
• Looking for Class C /25 IP Subnetting
• IP Class C /25 Subnetting Exercise

#### 1.  Understanding IP Address and Subnetting

An IP address (Internet Protocol Address or often abbreviated IP) is a series of binary numbers between 32 bits to 128 bits that are used as identification addresses for each host computer on the Internet network.

In other words, an IP address is a line of numbers that belongs to every device such as a computer, laptop, cell phone and others that are connected to an internet connection.

Please note that the numbers on each device are different, which is useful for avoiding conflicts with the IP address.

Subnetting is the process of breaking down an IP network into smaller sub-networks called "subnets".

Subnetting is used to make it easier for computer network managers (System Administrators, Network Administrators, and ordinary users) to manage the network, allocate IP addresses for each room and building as needed.

#### 2. Looking for Class C /25 IP Subnetting

The result of Class C /25 IP Subnet is 11111111.1111111.11111111.10000000 or 255.255.255.128. The number of IP addresses that can be used is 128 (126) IP addresses.

The following is a calculation table for Class C IP Address Subnetting:

• CIDR (Classless Inter-Domain Routing)
• JIP (Number of IP Addresses)

 CIDR /24 /25 /26 /27 /28 /29 /30 /31 /32 JIP 256 128 64 32 16 8 4 2 1 SM 0 128 192 224 240 248 252 254 255

Good friends, see, above there is a table to make it easier for us to calculate Class C IP Address Subnetting.

In the table there are 3 Rows, namely
• CIDR (Classless Inter-Domain Routing)
• JIP (Number of IP Addresses)

Okay, let's go straight to the matter of discussion, for example the IP Address  192.168.10.20/25 and we do it in the following way:

192.168.10.20/25
JIP  = 128 - 2 = 126
SM = 255.255.255.128
IP N = 192.168.10.0
IP B = 192.168.10.127
IP R = 192.168.10.1 - 192.168.10.126

Explanation :

• JIP (Number of IP Addresses)
• IP N (IP Network)
• IP R (IP Range)

To get the number of IP addresses that can be used, friends can see in the subnetting table above at /25, the number of IP Address is 128.

Looking for the Number of IP Addresses = 128 - 2 = 126 (then found the number of IP address that can be used  126 Host)

Search for subnetmask > Look at the Row Subnetmask, if /25 then the subnetmask is 128 or 255.255.255.128.

Search for IP Network > JIP (Total IP Address) multiplied by the result of the number that is close to the last 8 bits or 20. Then 128 multiplied by how much is closer to 20.

last 8 bits are 192.168.10.20

128 * 0 = 0  Means the first answer is the correct one. because it is near the number 20 and not greater than the number 20
128 * 1 = 128
Then IP Network = 192.168.10.0.
Search for IP Broadcast > JIP (Total IP Address) multiplied by the number that is greater than the last 8 bits or 10. Then 128 is multiplied by what is the result that is greater than 20. so
128 * 0 = 0
128 * 1 = 128
The correct answer is 128 * 1 = 128 , then the result is 192.168.10.128.
To get Broadcast IP, the last 8 bits are subtracted - 1. So we get IP Broadcast namely :

Search for IP Range

The IP Network obtained earlier was 192.168.10.0, then added + 1 to the last 8 bits (0+1), then the IP Network obtained was = 192.168.10.1.

192.168.10.0 + 1 = 192.168.10.1

To get Broadcast IP in the IP Range then 192.168.10.127 min -1, then we get Broadcast IP = 192.168.10.126

192.168.10.127 - 1 = 192.168.10.126

Then the result on the IP Range is:  192.168.10.1 - 192.168.10.126.

So the results of the subnetting process at CIDR /25 above are as follows:

192.168.10.20/25
JIP  = 128 - 2 = 126
SM = 255.255.255.128
IP N = 192.168.10.0
IP B = 192.168.10.127
IP R = 192.168.10.1 - 192.168.10.126

Another example of questions in the discussion of Class C /25 IP Subnetting

IP = 192.168.40.130/25
JIP  = 128 - 2 = 126
SM = 255.255.255.0
IP N = 192.168.40.128
IP B = 192.168.40.255
IP R = 192.168.40.129 - 192.168.40.254

#### 3. IP Class C /25 Subnetting Exercise

1. 192.168.10.100/25
2. 192.168.200.2/25
3. 192.168.99.91/25
4. 192.168.200.1/25
5. 192.168.199.199/25

I think that's all I can say in this article entitled How to Calculate Subnetting IP Address Class C /25. InsyaAllah, the next one will be continued, friends. Thank you for visiting :). I hope this tutorial is useful for all of us.

That is all and thank you. Best regards, ceflox.com