Therefore, only the following masks can be used with Class C networks ( Table A). Since the Class C mask only uses the last octet for host addressing, we only have 8 bits at our disposal. To make smaller networks, called subnetworks, we will borrow bits from the host portion of the mask. If we use the default subnet mask with a Class C network address, then we already know that three bytes are used to define the network and only one byte is used to define the hosts on each network.

Also, by determining the subnet and broadcast addresses, we can easily determine the host addresses because the valid host range is always the numbers between the subnet address and the broadcast address. Why? Because these are not valid host addresses and cannot be assigned to host configurations. Once the subnet is determined, the broadcast address must be found. The valid host range of the subnet used to configure hosts.By creating smaller networks, we can more effectively get data to each host.Subnetting a Class C networkSo you understand why you want to subnet, but how do you do it? Your goal is to look at an IP address and subnet mask of a host and then determine three things quickly: For IP to communicate with a host, the IP address must be known, and the router connected to the network on which this host is located must also know the hardware address of the house.What if a city didn’t have many blocks but just one long street? The mailman would go crazy trying to get the mail delivered to each house correctly because he would have to know the address of every house. Think of the addresses on the houses as the hardware addresses of a host. Each house on this network is known by the street and by the address. Think of a network like streets in a city. First, we need to discuss why we want to subnet a network and the advantages of doing so.īy creating smaller IP networks (instead of having one large network), we can obtain better security, smaller collision and broadcast domains, and greater administrative control of each network. Since this is a complicated, involved process, I will only discuss the process of breaking up Class C networks.

In this Daily Drill Down, I will continue our discussion of IP addressing by exploring the process of taking a large IP address range and dividing it into smaller, more manageable pieces.

SEE : Download: Time management tips for tech professionals (TechRepublic) Although IP addressing isn’t a network administrator’s favorite task, it’s a critical skill that you must have. Let’s face it, some day you are going to have to subnet a network. For more info, visit our Terms of Use page. This may influence how and where their products appear on our site, but vendors cannot pay to influence the content of our reviews. We may be compensated by vendors who appear on this page through methods such as affiliate links or sponsored partnerships. Todd Lammle walks you through clear instructions and step-by-step examples to help you learn this skill. From MCSE to CCNA to RHCE to CNE, you'll have to know it and know it well. Subnetting a Class C network can be a tricky process to master.

Classful subnetting chart