The Subnet Mask

6 minutes
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All righty, welcome back. Now, key, the answer to everything. Holy Grail, right? The subnet mask that's going to give you the answer to everything that you made a request and ask an IP address questions obviously. Normally, we're used to see a subnet mask. I'll put the decimals in later pow, pow, pow, okay.

Normally we just saying 25525250 right? That is the now that you know that is a default Class C subnet mask and let me get this out of Right now, the subnet mask, yes, I raised it up an octave. The subnet mask does not turn a Class A address into a Class B address doesn't do that. If you look at a Class A, which the default is a cider eight, but you have a class A address with a cider 24 domains, you've submitted that class A, but it's still a Class A. So the subnet mask what it does, it tells you hey, here's the line. This is your network.

And these are your host. That's what it tells you in ipv4. Okay, which side belongs to network and we're sorry, belongs to the host. That's it. As simple as that may sound, it is crucial as we go on to the next sections and the following sections. You'll start getting more of an understanding of like, the subnet mask okay.

Got it. I know what Okay, cool. All right, because when we do when we subnet, we need to mess around with some of the mapping to move with this law imaginary line going back and forth, as I like to call out there. Now the magical line, the magical line, right? And you can have a different subnet mask. But that's what the subnet Magda does.

It says, What part of your addresses to network? What part of your addresses to host? And I said, that's what it does. No more, no less. Don't get anything crazy in your head about it. In routers when you're doing routing protocols, alright.

Let's say like this is vector routing protocols. You need to make sure and I know getting a little bit off tangent. I'm gonna erase this, you shouldn't. And you have things to look at anyway. Okay. If you do want to say rip this is when you're doing read those as an example, right.

If you want the subnet mask To go out on the updates, you need to make sure that you do all your network statements and all that you're going to say, no outro hyphen, summary. And man, and this is not even part of this course. But you know what? I'm going to tell it to you anyway. Because if you don't tell it this, it will not send that because this is a distance vector routing protocol, it does not send the subnet mask out on the updates. So if you have a class A, let's say, the whole network has a class eight, right?

Well, where's it going to send the information? How does it know what node is going to go to? I don't know. Everybody has a 1010 1010. I don't know where to send it to. Well, if you say this, because it'll summarize by default.

It says, Listen, do not summarize. Send the subnet mask information on your updates, so we know exactly when we're going to okay and he Do it. Alright. So that's important because if you don't, you'll never get anywhere you may get somewhere you may not. So you're going to run into issues. And that sounds like a very good test question to me.

Okay. So be careful with this command in the routing protocols. Because the subnet mask like I told you is extremely important. It is the key to everything in networking. Okay, it is the key to area networking, as you will shortly see. All right, now we're going to use that for everything.

Okay. The Sona mask, two subnets. summarize everything. vlsm is the subnet mask. Okay, that is crucial. And all it is is saying, hey, there's a network, hey, these are your hosts.

Here you go. All right, and what masks are gonna actually put in there, because you can put in the wrong mask, the router will yell at you. Of course in a certification or in a test they'll know if it's a print screen. It's not gonna yell at you, obviously. But in a real world scenario, you put in the wrong mass, mass for address given, okay, and your computer will say something like, oh, by mask out of range or something to that effect, it'll scream at you, if I'm in a program and said, Hey, ROM as they're done, you know, some, you know what, they'll get your attention, but either way your computer's your devices will let you know that if you put an IP address with the wrong mask, it will give you some sort of error if you did it wrong. Are they saying hey no, no no no, you can put this mask based with this address, because there may be overlapping without address.

So that is the kind of errors that will give you overlapping back mass Rogers given out of range whatever the case may be. So the subnet mask it is crucial, it is crucial and again to reiterate, network host, okay, based on those decimals that we put up there, and they will change when we get to Sunday. They'll get a little bit more on that in the next

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