Client-side Virtualization - CompTIA A+ 220-1001 Prof Messer





  • Linux Ubuntu? LOL

    That would be Ubuntu Linux.



  • Hey, he made a point that it has been around since the 1960s. Thank goodness.



  • He shows VirtualBox in the examples. That's nice.



  • Overall, this seems like a good video. Haven't quite finished it yet, but the info seems to be clear and accurate. Stuff that so many people often get wrong. Good to see good info when the A+ has such a reputation for getting the basics screwed up.



  • I thought an OS memory usage was not that high...is this not the case?



  • @mary said in Client-side Virtualization - CompTIA A+ 220-1001 Prof Messer:

    I thought an OS memory usage was not that high...is this not the case?

    Define "not that high?" Let's take Windows for example, a Windows system doing any normal amount of tasks will use at least 2GB while basically idle and easily 4GB if doing anything, and easily 6-8GB if you are just surfing the web a lot. A typical computer today comes with either 8GB or 16GB of RAM.

    So if you are virtualizing a system, it needs exactly the same amount of RAM as a physical system. So if your virtual system needs a minimum of 4GB and practically needs more like 8GB, and you run two of those on top of your existing system which itself needs close to 8GB, suddenly you need 24GB total, so the numbers get really big, really fast.

    Now if you are using Ubuntu Linux and don't run a graphical desktop, you could get a virtual system up and running with maybe 400MB of RAM, a very, very far cry from 4GB. So it all depends what you are doing.



  • A few of the practice questions on the A+ deals with mac filtering. Is that what he is talking about when configuring each instance of the OS with it's own address or is this another layer you can add on?



  • @mary said in Client-side Virtualization - CompTIA A+ 220-1001 Prof Messer:

    A few of the practice questions on the A+ deals with mac filtering. Is that what he is talking about when configuring each instance of the OS with it's own address or is this another layer you can add on?

    MAC filtering is uncommon (and generally impractical) in the real word. It's one of those "mostly fake" "security by obscurity" things that newbies get taught to do that sounds good to management, but techs know is not going to stop anyone. It's more of a pain than anything, and mostly if for cases where someone in testing on their tinfoil hat for size.

    But basically every device has a unique MAC address, this is how Ethernet or Wifi tell one device from another. It's their "machine address". MAC filtering is when you make a list of the MAC addresses allowed on your network (there is zero value to making a list of ones that are banned because anyone can just change their MAC address to anything that they want.)

    For normal people, 99.9999% of the world, you don't change your MAC address from the default, which is always set by the manufacturer following simple global guidelines. It's a UUID. So MACs always "just work", you ignore them. They are handled at a layer below IP addresses and you don't need to think about them.

    It's not the OS that has a MAC address, it's the NIC that the OS is using. It's the address of the "Ethernet device."



  • IP, the Internet protocol, doesn't work on its own, it's a very "high level" protocol. It has to ride on top of other things, like Ethernet. In today's world, it's always Ethernet or Ethernet over wireless (aka Wifi.) Thirty years ago, Ethernet had lots of competitors like Token Ring, today it really doesn't have any competitors except super, duper rare Infiniband. Anything other than Ethernet or Infiniband as an underlying protocol for IP is just a "lab experiment" and not useful in the real world. Technically things like USB and FibreChannel can do the job, but have to purpose.

    Part of what makes Ethernet so good is that all of the work is "automatic." There is zero configuration needed or warranted from the end users, even at initial setup. If your goal is just to build an Ethernet network and nothing more, all you need is a switch of any size, and to plug computers (or devices) into it, that's it. Ethernet is just sort of magic. It's also so basic that it is almost unusable, it needs something like IP on top of it to do anything that you'd actually want to do. It's not enough on its own, it's really just a building block to IP.

    But you CAN mess with the Ethernet layer and one of the easiest things that you can do is to modify your MAC address.



  • @mary if you want to see some MAC addresses on your network try the arp command on Fedora Linux. ARP is the "Address Resolution Protocol" and it is the protocol that maps the ethernet devices with MAC addresses to the IP addresses that are assigned to them. By running arp you will see a list of the IP addresses that your desktop knows about, and the list of the MAC (called HW Address for Hardware Address) to which they are mapped on your home network.



  • On Windows, if you install the Advanced IP Scanner like this choco install advanced-ip-scanner -y and run it, it will scan your network and show you a list of all MAC addresses that are active on it, and it will use that MAC address to list the manufacturer of the device in question (since a native MAC address has to have the manufacturer's registered ID in it as part of the address.)



  • @scottalanmiller thanks for clearing that up!



  • @scottalanmiller As one of the tinfoil hat wearers around here, even I don't thing MAC filtering is anything other than headache and time sync.