Local Area Network LAN Review – CompTIA Security – In this article you will see a quick review of a lot of important denizens of our Local Area Network ergo LAN review. So what I’d like to do right now is run through a lot of stuff on switches and routers and such that hopefully you would already know but for completeness let’s just go ahead and do a quick review starting with switches.
So we have a standard net gear switch. Now remember switches filter and forward data based on MAC addresses. So switches tend to pretty much work automatically out of the box. However there are some features that we’re going to see on the exam I want to just make sure you know. So let’s go through those. The first one is the concept of a VLAN.
So if somebody sends out a broadcast it goes out to every other port. However if we want to we can actually split up that single broadcast domain into multiple broadcast domains known as VLAN’s. So in essence what I could do is I can set up a VLAN and VLAN’s have numbers, you do like VLAN one, VLAN two, you really can’t say like VLAN Timmy, it doesn’t work that way. So to see this what I’ve got is the configuration screen up so let’s take a look over here. Now this machine is right out of the box. Basic Local Area Network
I have done really no configuration to it whatsoever. I also need to warn you as there are tons of settings in here that I am not going to be covering in a quick review we’re just going to hit the ones that I want to make sure you’re aware of for the exam. So first of all let’s go over to switching. Now, if you take a look on this system I’m going to click on VLAN here you’ll see that it has three built in VLAN’s. Number one which is the default VLAN and then these two others which I doubt I would ever use. Voice VLAN and audio VLAN.
Spanning Tree Protocol
Now one of the dangers with switches is that you can accidentally plug them together in such a way that you can create loops or what we call bridge loops. Now a bridge loop will basically knock a network down instantaneously. So what we’ve developed with any good switch is something called Spanning Tree Protocol or STP. So the nice part about STP’s, you pretty much just have to turn it on and let’s go back in here and let’s make sure STP’s even lit up on these guys.
Now there’s STP and then Rapid STP and we pretty much just use Rapid STP and then BPDU flooding is just if we moved boxes around it knows how to track that type of stuff. So really all I need to do in this particular case is make sure that this guy is turned on.
If switches filter and forward based on MAC address or Layer 2 routers filtered forward based on IP address or Layer 3. So the term layer 3 switch is a very common term that can be used interchangeably with the word router. So if routers filter and forward based on IP addresses routers are going to act as the doorway or the interface between different network IDs. And in this particular case this simple router is separating two different network IDs. On one side is 192 168 4. And we’ll just put dot 0 since there can be lots of computers in there. So it’ll be 190 168 4 dot one for the router itself dot 2, dot 3, dot 4, whatever.
A firewall is a piece of software that is commonly run on a gateway router which protects us from the evils of the Internet, so it can forward and filter based on port numbers, based on IP addresses, URL’s, all kinds of different stuff. So we would call this a network firewall because the gateway is running the firewall software and protecting us from the evil of the Internet. So this was a quick and dirty review of some of the terms that you’re going to be seeing on the exam. I hope you’re familiar with all these terms and can appreciate that I’m doing a very light touch to it. However if there are any terms that I just brought up that you’re unaware of I wouldn’t think it would be too bad of idea to consider for example my Network+ video series to help you dial in and make sure you really understand what do switches and routers really do.