Configuring IPv4 is more than just adding a single IP address. In this video, you’ll learn about the structure of an IPv4 address and the important configuration options to use IPv4 on your network.
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As you’re configuring workstations, servers, routers, and other layer 3 devices, you’ll be working a lot with IP addresses, subnet masks, and other parameters that are necessary to perform IPv4 networking. For example, to manually configure an IP address on my device, I have to add the IP address itself, I have to specify the subnet mask, and I have to specify the router. I can also add DNS server information so that I’m able to perform DNS lookups when I’m using this device.
Let’s start with the IP address. Every device needs a different IP address, and you’ll see it represented as four separate values with a period in between. So 192.168.1.165 is a properly formatted IP version 4 address. If you are configuring a layer 3 device, then you need more than just the IP address. You need both the IP address and the subnet mass to be able to communicate on a particular network.
The subnet mass values are used by that local device to determine what IP subnet it happens to belong to. It’s not a value that is commonly transmitted across the network, so you’ll often ask the network administrator to provide both the IP address and the subnet mask for a particular device. With just the IP address and the subnet mask, you’re able to communicate to other devices on your local network.
But if you ever want to communicate outside of your local IP subnet, then you’ll need the default gateway or router IP address. So on my network the router IP address might be 192.168.1.1. That means if I wanted to configure this device to communicate to other devices on my local subnet and communicate devices outside of my local subnet, I’ll need to provide the IP address, the subnet mask, and the default gateway.
A loopback address is an IP address that all devices happen to have internal to those devices, and they all happen to be using exactly the same loopback address range. For example, 127.0.0.1 is a very good example of a loopback address that’s inside of your computer. You don’t have to configure this address. There’s no set up to make this particular address work. If TCP/IP is running on your computer, then your machine is going to have a loopback address inside of it.
The defined range of a loopback address is 127.0.0.1 through 127.255.255.254, but you’ll find that some operating systems won’t recognize other loopback addresses. They’ll only know 127.0.0.1. We’ll often use this loopback address as a way to reference our own computer. So if we want to make sure that the TCP/IP stack is working properly on our computer, we might ping our loopback address of 127.0.0.1.
In IP version 4, there’s also a block of addresses that will never be used on any layer 3 device. These are reserved addresses, and they range between 240.0.0.1 through 255.255.255.254. Although we often associate an IP address with a physical network interface card, we can also assign IP addresses to virtual devices. You might have virtual machines that might be running on your computer, and each one of those virtual machines may have a virtual IP address associated with it or you might have a router that has virtual IP addresses assigned to virtual interfaces on the inside of that router.