#CLASSFUL SUBNETTING CHART HOW TO#
#CLASSFUL SUBNETTING CHART MAC#

You pronounce it as “configure a slash 24 mask on that network.” It’s just an easier way of saying “configure a 255.255.255.0 mask on that network.”įigure A is an example of assigning masks on a case-by-case basis or, in this instance, LAN by LAN. It saves you from typing, or pronouncing, the whole mask. The slash (/) indicates the number of mask bits turned on.

For example, on a WAN point-to-point link, you need only two IP addresses, so you can use a /30 mask. Once you have an idea what your network will look like, write down the number of physical subnets you have and the number of hosts needed for each subnet. If you’re not using subnet zero, subtract two from each number in the Subnets column in Table A above. This chart assumes you can use subnet zero. Table A lists all the available Class A subnet masks: However, with a Class A mask, you have 24 bits to manipulate, so this isn’t typically a problem. The more bits you borrow, the more subnets you can have, but this means fewer hosts per subnet. If you wanted to create smaller networks (subnetworks) out of a Class A network ID, you’d borrow bits from the host portion of the mask. The last three octets of a Class A subnet mask are used to address hosts on a LAN the 24 bits you can manipulate however you wish.

#CLASSFUL SUBNETTING CHART MAC#

They need to know only the “street” on which hosts are located and that the MAC address is used to find a host on a LAN. Routers aren’t concerned about host addresses. Routers use the network portion to send packets through an internetwork. If you need more information on subnetting other types of networks, take a look at Todd Lammle’s other subnetting articles: “Subnetting a Class B network address,” and “Subnetting a Class C network address.”Ĭlass A subnet masks must start with 255.0.0.0 at a minimum, because the whole first octet of an IP address (the IP address describes the specific location on the network) is used to define the network portion (the network portion describes the “street” that IP addresses are located on).

#CLASSFUL SUBNETTING CHART HOW TO#

Here, I will explain Class A subnet masks and how to assign valid subnets and host addresses to provide flexibility in configuring your network. Getting up to speed with subnetting Class A addresses requires a little forethought, some basic information, and a lot of practice.

Although the Class A network has only 254 unique network addresses, it can contain approximately 17 million unique nodes, which can make subnetting such a network a nightmare. The Class A networking address scheme is designed for the government and large institutions needing a great deal of unique nodes. 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. Here, Todd Lammle offers a simple approach to this addressing. It can have a large number of unique nodes, which can prove quite a challenge. Class A subnetting is a form of network addressing typically reserved for the government and larger institutions.

Classful subnetting chart