How to Subnetting and find Subnet Mask, Network ID, Host IP Address

One Private C class IP Block is 192.168.222.0/24

1. 10 PCs in the CSE Department

2. EEE Department at 10 PC

3. BSTE Department at 10 PC

4. BBA Department at 12 PC

5. ENGLISH Department at 5 PC

6. 5 PCs at LAW Department

7. Admission Department at 5 PC

8. Account Department at 5 PC

9. Admin Department at 5 PC

10. IT Department at 5 PC

11. Library on 2 PCs

12. 35 PCs in LAB General

13. In LAB CSE 50 PCs need an internet connection

For this, how do Subnetting your Network

Step-1: First we calculate that we need (10 + 10 + 10 + 12 + 5 + 5 + 5 + 5 + 5 + 5 + 2 + 35 + 50) = 158 IPs and 13 subnetworks.

Step-2: We know that in C class IPv4 address (8: 8: 8: 8 = 32bits) 3 Network 1 Host (N: N: N: H) is used. Since there are three networks in C class, it's default bit is 24 and its default subnet mask is 255.255.255.0. We know that an Octet (128 + 64 + 32 + 16 + 8 + 4 + 2 + 1) = 255 Since three Octets are used in C class, its default Subnet Mask is 255.255.255.0

Step-3: Now, we will start subnetting our 192.168.222.0/24 IP. When doing Subnetting, you have to notice who needs the most IP first and who needs the least IP.

Most (50) IPs are required in LAB CSE.

We know a formula for finding Host IP 2N-2

N = unused host bit

-2 = 1 network address and one broadcast address

If we need an unused host bit for 50 IPs, then we need to increase the bet by 2, since we have 8 bits in an Octet. If it is network-1, we can write 192.168.222.0/26. Our default bit was 24. Since we have increased 2 bits, we have written 26 instead of 24.

Network-1: CSE LAB (50 PCs)

192.168.222.0/26

N = Total Bit - Useable Bit (32 - 26) = 6

2^6 - 2 = 64 - 2 = 62 hosts

Network Address: 192.168.222.0/26

1st Host: 192.168.222.1

Last Host: 192.168.222.62

Broadcast Address: 192.168.222.63

Subnet Mask: 255.255.255.192

We know,

1 bit = 128

2 bits = 192

3 bits = 224

4 bits = 240

5 bits = 248

6 bits = 252

7 bits = 254

8 bits = 255

Since we have used 2 bits, its subnet mask has been 192

Network-2: General LAB (35 PCs)

192.168.222.64/26

2^6 - 2 = 64 - 2 = 62 hosts

Network Address: 192.168.222.64/26

1st Host: 192.168.222.65

Last Host: 192.168.222.126

Broadcast Address: 192.168.222.127

Subnet Mask: 255.255.255.192

Since we have used 2 bits, its subnet mask has been 192

Network-3: BBA Department (12 PCs)

192.168.222.128/28

2^4 - 2 = 16 - 2 = 14 hosts

Network Address: 192.168.222.128/28

1st Host: 192.168.222.129

Last Host: 192.168.222.142

Broadcast Address: 192.168.222.143

Subnet Mask: 255.255.255.240

Since we have used 4 bits, its subnet mask has been 240

Network-4: CSE Department (10 PCs)

192.168.222.144/28

2^4 - 2 = 16 - 2 = 14 hosts

Network Address: 192.168.222.144/28

1st Host: 192.168.222.145

Last Host: 192.168.222.156

Broadcast Address: 192.168.222.159

Subnet Mask: 255.255.255.240

Since we have used 4 bits, its subnet mask has been 240

Network-5: EEE Department (10 PCs)

192.168.222.160/28

2^4 - 2 = 16 - 2 = 14 hosts

Network Address: 192.168.222.160/28

1st Host: 192.168.222.161

Last Host: 192.168.222.174

Broadcast Address: 192.168.222.175

Subnet Mask: 255.255.255.240

Since we have used 4 bits, its subnet mask has been 240

Network-6: BSTE Department (10 PCs)

192.168.222.176/28

2^4-2 = 16 - 2 = 14 hosts

Network Address: 192.168.222.176/28

1st Host: 192.168.222.177

Last Host: 192.168.222.190

Broadcast Address: 192.168.222.191

Subnet Mask: 255.255.255.240

Since we have used 4 bits, its subnet mask has been 240

Network-7: ENGLISH Department (5 PCs)

192.168.222.192/29

2^3 - 2 = 8 - 2 = 6 hosts

Network Address: 192.168.222.192/29

1st Host: 192.168.222.193

Last Host: 192.168.222.198

Broadcast Address: 192.168.222.199

Subnet Mask: 255.255.255.248

Since we have used 5 bits, its subnet mask has been 248

Network-8: LLB Department (5 PCs)

192.168.222.200/29

2^3 - 2 = 8- 2 = 6 hosts

Network Address: 192.168.222.200/29

1st Host: 192.168.222.201

Last Host: 192.168.222.206

Broadcast Address: 192.168.222.207

Subnet Mask: 255.255.255.248

Since we have used 5 bits, its subnet mask has been 248

Network-9: Admission Department (5 PCs)

192.168.222.208/29

2^3 - 2 = 8 - 2 = 6 hosts

Network Address: 192.168.222.208/29

1st Host: 192.168.222.209

Last Host: 192.168.222.214

Broadcast Address: 192.168.222.215

Subnet Mask: 255.255.255.248

Since we have used 5 bits, its subnet mask has been 248

Network-10: Account Department (5 PCs)

192.168.222.216/29

2^3 - 2 = 8 - 2 = 6 hosts

Network Address: 192.168.222.218/29

1st Host: 192.168.222.218

Last Host: 192.168.222.222

Broadcast Address: 192.168.222.223

Subnet Mask: 255.255.255.248

Since we have used 5 bits, its subnet mask has been 248

Network-11: Admin Department (5 PCs)

192.168.222.224/29

2^3 - 2 = 8 - 2 = 6 hosts

Network Address: 192.168.222.224/29

1st Host: 192.168.222.225

Last Host: 192.168.222.222

Broadcast Address: 192.168.222.231

Subnet Mask: 255.255.255.248

Since we have used 5 bits, its subnet mask has been 248

Network-12: IT Department (5 PCs)

192.168.222.232/29

2^3 - 2 = 8 - 2 = 6 hosts

Network Address: 192.168.222.232/29

1st Host: 192.168.222.233

Last Host: 192.168.222.238

Broadcast Address: 192.168.222.239

Subnet Mask: 255.255.255.248

Since we have used 5 bits, its subnet mask has been 248

Network-13: Library (2 PCs)

192.168.222.240/30

2^2 - 2 = 4 - 2 = 2 hosts

Network Address: 192.168.222.240/30

1st Host: 192.168.222.241

Last Host: 192.168.222.242

Broadcast Address: 192.168.222.243

Subnet Mask: 255.255.255.252

Since we have used 6 bits, its subnet mask has been 252

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