Join Mike Meyers for an in-depth discussion in this video Coaxial cabling, part of CompTIA Network+ (N10-006) Cert Prep: 2 The Physical Network.
- If you wanna pass the Network+ exam, you've got to know about coaxial cable. Even though coaxial cable really isn't used in networking too much anymore, it's used enough that we need to be able to discuss the aspects of what makes coaxial cable, coaxial. So what I wanna start off with is this big ol' evil cable. This is an original. What was known as thick ethernet cable since, a long, long time ago. Let's just say I had a lot of hair back then. Anyway, even though we don't use this cable for networking anymore, it's a good way to explain coaxial.
So if you take a look at this, this is a very classic piece of coaxial cable. We've got a little conductor here in the center, and then we've got some insulator, and then another conductor on the outside. And that's where the term coaxial comes from. Because you have two conductive materials that are centered around a single axis. So anytime you see that, you always know that you're gonna have two types of conductors. And that's what coaxial cable's all about. Now when you're talking about a coaxial cable, there are two things to keep in mind.
Number one, the name of the cable. This type of cable was called, still is called RG8. So coaxials will always have a number that starts with RG and then a number that separates them. The other thing to keep in mind is that coaxial cables are measured by an impedance. So for example, this RG8 cable has an impedance of 50 Ohms. Now... Let's take a look at another type of coaxial. This was also used in networking a long time ago. It's kind of faded out and this particular type of cable is called RG58.
Now I what I want you see more than anything else is this connector. Oh by the way, RG58 also runs at a 50 Ohm impedance, but it's the connector right here that the Network+ is interested in. This is called a BNC, Bob Nancy Charlie, connector. And here's something to connect it into, give it a little twist, and it's connected. This little guy right here is known as a T-connector. Back in the old days, we would plug this part into the network card and each end would run out to other network cards. Back in the old days, there were no switches or hubs.
We just ran everything on a daisy chain like this. And who was ever on the end, would get this little guy. This is a Terminator. And you would put that at the end of each run of cable. Now, even though RG8 and RG58 are gone, there is one place that we still see a lot of coaxial. And that's with cable modems. So I've got right here a piece of RG6. RG6 is 75 Ohm, and it's gonna be distinct, and it's gonna have what's known as an F-connector. Anybody who has a cable television's probably seen this.
It's a screw-in connector and it's pretty much a guarantee that you've got a cable connection of some type. So the F-connector is very important. So, even though coax isn't used that much, it is on the Network+, and if you've got a cable modem network, you're definitely gonna be running into some of this. So remember, you've got different grades, will now always start with an RG. RG6 is the big one I want you to remember 'cause that's one we use today more than anything else, and that's for cable modems. And also make sure that you can recognize a BNC connector from an F-type.
It will be on the test.
We are now a CompTIA Content Publishing Partner. As such, we are able to offer CompTIA exam vouchers at a 10% discount. For more information on how to obtain this discount, please download these PDF instructions.