CompTIA Network+ N10-008 – Networking Tools and the Command Line

  1. Networking Tools (Part 1)

Networking tools. So now that we’ve covered troubleshooting, let’s move into the different tools we use to conduct some of this troubleshooting. First, we need to look at the physical cabling because it still serves as the backbone of our networks. Even with wireless networking and lots of virtualization, many network problems can be reduced through proper installation and configuration. So if you build it right the first time, it’s going to solve a lot of your issues. Next, we want to look at the multiple types of hardware and software tools that are out there for us to be able to diagnose, isolate, and resolve any of our network issues. And it’s important to understand these tools not only on test day but also in the real world, because these different tools, management devices, and protocols are used by us as network technicians to solve issues on a daily basis. For the exam, you don’t need to know how to use these tools, but you do need to be able to identify which tool is used for what thing.

And we’ll go through that as we go through this lecture. Now, the first one is an electrostatic discharge strap, or ESD strap. This allows all the static buildup that happens in your body to be discharged through this blue wristband into that alligator clip that’s touching bare metal instead of going into those circuits and causing issues. If you recall, when we discussed bad modules in Layer 2 troubleshooting, I mentioned that if you had to replace a module, you should use an ESD strap. The static discharge can have several thousand volts of electricity, but it’s at a low amperage, so it won’t hurt you except for that little shock that you feel. But it will hurt our components and destroy routers, switches, and other sensitive components. Next, we have a mustimeter. And a mustimeter is a way to check the voltage, amperage, or resistance of a copper cable. This can be used to verify if a cable is broken or not by checking the resistance. If I check a copper cable from end to end, I should get zero resistance because it’s copper. If there is a high level of resistance or an overload, that would mean that there’s actually a break in the cable.

Now these are used to test power sources as well. So before I plug in a computer or a switch or a router into an outlet, I might want to check that outlet and verify I’m getting the right voltage. Is it between 115 and 125? in the US. That’s standard for us. If you’re in Europe, you should be getting 230 to 240 volts AC. Either way, you can test this using your mustimeter and make sure that you have good, clean power. Next, we have the loopback device, and these are going to be different depending on if you’re using Ethernet or if you’re using fiber. If you’re using Ethernet, your transmit and receive pins are going to be swapped, your transmit plus to your receive plus, or pins one to three and pins two to six, which is your transmit minus to your receive minus.

It looks like this green and white device up here on the right. And you can actually build your own loopback device by using some Cat 5 cable and a connector. Now for fiber, it’s going to transmit the fibre back to the receive fiber, and so it just makes a quick loopback as shown here at the bottom of the screen, where I have an SC connector to an SC connector. This is used with diagnostic software to test the connectivity of a We have a crimper. A crimper is used to attach those plastic RJ45 connectors to the end of a cable. This will allow technicians to make cables of varying lengths and sizes as opposed to having to use store-bought ones. This will allow you to physically crimp that plastic connector. For networks, we use an RJ-45 connector, and for phones, we use an RJ-Eleven. There are two holes in this crimper, as you can see in the tool. The larger one is for RJ 45, and the smaller one is for RJ 11. Next, we have a cable tester. So if I crimp my own cables, I want to test them and make sure they’re good. I can do that using a cable tester. Or maybe you’re having a layer one issue and you want to see if the cable works. That’s what a cable tester is for. It checks the continuity of each of the eight wires inside the cable to ensure there are no breaks. This will verify the pin outs to make sure you put them in the right spot and that there’s continuity all the way through. And there are different types of testers for different types of cables. The one on the right, for instance, only has two options.

As shown on the right, it supports BNC and Ethernet Cat. 3, Cat. 5, Cat. 6, and Cat. 7. The one on the left is a multitasker. It will support IDE SATA, RJ 45, fiber, DB 25, DB Nines, and pretty much anything else you can throw at it. Which one you use will be determined by your network. We use the one on the left at my college because we teach all of these as part of the plus and network plus curriculum. When we start dealing with the one on the right, that’s usually what I use in my daily business when I’m dealing with Cat5 and Ethernet networks pretty much exclusively. Next, we have a cable certifier, which is used with existing cable to determine its category or data throughput.

I can connect it to your network and determine whether it’s Cat 5, Cat 6, Cat 5 E, or Cat 7. It will tell me, based on its frequency range, what the throughput of that cable is, and a standard output is shown here on the screen. Notice that I have a wire map that shows my pins are correct and that it’s a straight-through cable. It also tells me how long it is, which is 10 feet in this case. It’ll tell me what the delay is, what the resistance is, and all of that good information. So it performs the same functions as an actable tester, but it goes a step further by providing additional information, such as length. This can be used to determine if the length is right and if the cable has been crimped properly, just like a cable tester. But because of all this extra information, they are a more expensive device. You can get a simple cable tester for under $10, but a cable certifier might cost you several hundred dollars. Next, we have the punch-down tool.

Now, if I’m going to be using a 66- or 110-block for either my phones or my networks, or even my network jacks in the wall, they all use punch-down tools to install those cables. This is going to terminate the wire on the punch-down block without stripping off the installation and cutting off the excess. So on the bottom left, you can see what this looks like on the back of a patch panel. On the bottom right, you can see this tool being used to connect to a network jack that would sit in your wall. It would just take out those eight wires. You flatten them out, put it over, and then there’s a little metal vampire clip, and the tool comes in and punches it down on top of it, which then allows it to be secure and in place and make those electrical connections.

Next, we have the butt set, and this is a piece of test equipment that’s used by telephone technicians to check for dial tone and verify that a call can be placed on the line. And notice that it has these little alligator clips. And these can be attached directly to those 66 blocks to be able to pick any single phone line that it wants to be able to make a phone call from. It also has dialing capability on the top of the handset. And when you put it up to your head, just like a phone, you can listen in or dial into those lines. It’s limited and used for network technicians, unless you’re working on DSL lines or you’re responsible for the interior wiring of your phone plant as well. Depending on how you have it configured, it can also connect to the punch-down block, as I said, or to a telephone line via a standard Relevel jack. Next, we have a toner probe. And a toner probe is going to allow a technician to place a tone generated on one end of the connection and use the probe to audibly detect the wire connected on the other side.

This is often referred to as a “fox and a hound” operation because the fox generates the tone and the hound is used to sniff it out and locate it using the toner probe. This set here is the one that I personally use inside my network and that allows me, if I have an unlabeled network, to figure out which wire is connected to a certain jack inside the building.

Next, we have the time. Domain Reflectometer And the time domain reflectometer, or TDR, is going to locate brakes and copper cables and provide an estimate of the severity and the distance to the brake. So if I have a cable running between my building and the building next door and I want to figure out where it’s been cut because somebody’s been digging between our buildings, I can do that. By connecting this, it will tell me that the brake is approximately 87 feet away based on the resistance and the fact that it responds to me, and I will know where to look for it. There’s also an optical version of this called the Optical Time Domain Reflectometer, which is used for fiberoptic cables, which is really helpful because your fiberoptic cables can be many miles long. Knowing that the brake is at 3.57 miles is far more useful than having to check this fibre cable by hand. The whole.

  1. Networking Tools (Part 2)

Networking tools. So because there were so many networking tools, I decided to break it up into two lectures. In this lecture, we’re going to focus on the software tools and testing the network once it’s been built and designed. So the first one is the speed test websites. Now there are a lot of them out there, but the one I tend to use is , as shown here on the bottom of the screen. This is going to verify the throughput from your client device all the way out to the Internet and back. Essentially, it’s going to download a large random file from the server and then turn around and upload it back. Now the server is going to time the amount of time that it takes to download that file and upload it again, and that will determine the connection speed. It will also do a ping test to determine the latency that you have between you and the server.

Now, this will determine your overall connection speed to the Internet. So if you’re paying for 100 megabits per second from Verizon or Comcast, you can go to and see if you’re getting about what you’re paying for. If you’re only getting 20 megabits per second but paying for 100, you also want to know that as well. Next, we have a throughput tester, which is a network appliance that you put inside your network to test it. And it will test multiple types of network interfaces by generating a high volume of random traffic for wired and wireless networks. So if you notice on this device, we have some fibre connectors, some RJ-45 connectors, and we even have some DB connectors, like a DB 25 or a DB 9. This is going to be used when prototyping your networks to observe how they’re going to respond under a heavy load. So when I’m designing a new network, I want to test it before I put customers on it, and this will allow me to do that.

You can also use it in your production networks—the ones that are already in place—to determine the actual throughput of the existing network. The next thing we have is what’s called a Bert, or bit error rate tester. This is going to generate a pattern at one end of the link, and you’ll analyse it at the other end to see if there are any errors. This is very common when using T-connections between you and the phone company to ensure that the cable is operational and the protocol over it is operational. Your bit error rate, or Beer, is determined by measuring your bit errors divided by the total number of bits transferred. So if I had one error out of 100 that I transferred, that would be a 1% error rate. This is a useful tool when troubleshooting interfaces on a cable or fiber, such as a T1, an E1, or even an OC connection. And, as previously stated, you will usually do this with your phone or telecom company. Next, we have environmental monitoring. So I have all of these switches and all of these routers in all of my telecom closets. How am I keeping track of them all? How do I know that the power is still on, that the cooling is still on, and that nobody’s broken or touched them? Well, that’s where environmental monitoring comes in. It can be programmed to notify you if the temperature or humidity level becomes too high or too low. And it can monitor your temperature, your humidity, your power, your airflow, and even your security. if you’re using cameras with it.

Next, we have a protocol analyzer. This is also known as a network sniffer. The most common one is Wireshark, but there are other ones out there, like Ethereal. This can be a standalone device or simply software running on top of a laptop. Essentially, it’s going to capture the traffic on your network, and then you can review that for problems between the communications of those devices. In the case here on the screen, you can actually break it down to the frames, the packets, and the segments—even down to the bit level with the ones and zeros shown at the bottom of the screen. And by doing this analysis, you can find all sorts of information about your network. Next, we have a wireless analyzer, which is a specialised piece of software that can be used to conduct wireless surveys to ensure you have the proper coverage and you’re preventing any of that non-desired overlap. So as you see on the left here, you can see the wireless repeater and a couple of other WiFi access points.

And so we can see that Bennett and Bennett’s repeater are both operating on channel 1, but nobody else is operating in channel 1, which gives us a good, strong signal without a lot of noise. Now on the right, you can see that I have a map of somebody’s house, and you can see the path that the technician walked around in blue as they were taking an analysis of the wireless environment. And as you can see, we have good coverage throughout this entire building. But that one back room, that conference room, is a little weak, as it’s shown in red as opposed to green. But this will still give you a good idea of where your weak points and your strong points are in your wireless network and where you might want to add repeaters or adjust your signal.

Next, we have “looking glass” sites, and a “looking glass” site is going to allow you to look at your network from the outside. This is extremely useful for router technicians, particularly those who work with the border gateway protocol. When you’re dealing with BGP networks, you’re dealing with those autonomous systems. And so being able to look at it from the outside and see how other routers are viewing your network is very, very helpful, and that’s what a “Looking Glass” site will allow you to do. And the last one we have, which we’ve talked about before, is remote connectivity software.

Things like RDP from Microsoft or Real NC or going to my PC It allows you to access a network client through a PC that’s located on a remote network. Now in my organization, we use remote connectivity a lot because when somebody calls our help desk, we don’t want to have to get up and walk all the way to that person’s office, which might be across the building or even in a different part of our state. And so if that’s the case, we would be able to just remote into them either from our cellphones, our tablets, or our laptops, take control of their computer remotely, and fix the problem. Now, this works great as long as your network is up and running. But if they’re not on the network, you’re still going to have to go out and visit them in person.

  1. Windows Command Line

Windows command-line tools Now, what is a command-line tool? Well, a command-line tool is used to configure and troubleshoot networks by issuing text-based commands at the operating system prompt. These commands can be used on either clients or servers, but they will be specific to the version of the operating system you’re using, whether it’s Windows 10, Windows 2016, or any other variant of Windows. Now, how do you access the command line?

In Microsoft Windows, you can quickly do this by pressing the Windows key and R. This will open the Run prompt; type CMD and press Enter. Alternatively, if you’re using an older version of Windows, like Windows Seven or earlier, you can click on Start and then go to Run and type CMD and hit Enter. If you’re using Windows Eight or Windows 10, just type the Windows key, then start typing CMD, and hit Enter. And it will bring up the command prompt, which looks like a box down on the lower right of your screen. Now, we’re going to talk about a lot of different commands and their usage for the Network Plus exam. You don’t need to be an expert on these tools, but you should understand the tools and a couple of key syntaxes, which I’m going to show you on the screen.

The first one is ARP, or address resolution protocol. This is going to show you the Mac addresses, those layer-two addresses for known IP addresses, or layer-three addresses. You can do this by typing ARPA, which will display your current ARP table. Now, after displaying that ARP table, if there’s a certain IP address you want to delete, you can use ARP d and the IP address. And this will delete the mapping for that IP address, just like you see here with ARP d 192, 168, 1. And the other one you want to know is S. So ARP S, your IP address, and a Mac address will statically create an ARP entry to force that IP address to always resolve to the Mac address provided. Now, as a network technician, the most common one you’re going to use is ARPA. What does this look like?

Well, here it is for you on the screen. Notice when I type in ARPA, it tells me what interface I’m using as a layer 3 IP address. And then it tells me all of the devices that I’ve talked to or know about, which I’ve found either dynamically because I’ve talked to them or statically because they’ve been assigned. And it’s just a mapping between IP addresses and Mac addresses, or physical addresses, as shown here. Because the broadcast address is FFFFF, our broadcast 100 2255 is assigned the Misaddress FFFFF. Then there’s IP configuration, or IP configuration.

This is going to display your iPad address information for a Windows PC. Now, the most common one is again “Ipconfig All,” which is going to show you additional information for all of your devices on your computer. If you just type in “IP configuration,” it will give you an abbreviated version of that. The other two you’re going to use a lot as a network technician are Ipconfig release, which will drop the configured DHCP address the PC has, and then Ipconfig renew, which will get a new IP address from the DHCP server. Now, what does this look like? Well, if you just do IP configuration, it looks like this: Notice that I have the DNS suffix, the IPV six address, my IPV four address, my subnet mask, and my default gateway. And that’s it. It’s just five pieces of information.

However, if I slash all, you will see a lot more information. It shows me my host name, what kind of routing is enabled, what my DNS suffix is, what my description of my adapter is, my Mac address, my Dot server, and my DNS server. All of this information is shown when you slash all. It’s a lot of information and is really helpful to you as a network technician as you’re troubleshooting issues. Now, the other thing I wanted to show you wit hip confit is that slash, release, and slash, renew, and you can see that here on this screen.

Notice I did an Ipconfig release, and now I have no IP address and no default gateway. That’s the top half. Now in the bottom half, you see, I did Ipconfig renew, and it went out and got a new IPV4, a new subnet mask, a new default gateway, and it also picked up a DNS server. But you can’t see that on the screen because it’s just showing you the abbreviated IP configuration portion. Next, we have ping. And ping is used to check the connectivity between two devices, and we most often use this for network troubleshooting. There are a couple of different ways to use ping.

The most common is just typing “ping” and the domain name that you want to go to. In my example, pinging will send out four pings and get four replies telling you if the site is up or down. This is the default one to use. Now, if you want, you can tell it that you want to get ten, twenty, or thirty pings, and you do that by using ping n and the number. So it’s ping and ten. will ping it ten times and then stop.

You can also set it up so that it just keeps pinging over and over and over forever. And that’s called a ping, and then the domain name. This might be useful if you want to verify that your Wan link is up all the time. In some places where I’ve worked, we’ve had applications running to their conclusion and simply leaving them on a screen. So we can look up and see that there’s always something up and running. And the last one is ping 6 and the domain name, which will force the ping to occur over IPV 6 as opposed to IPV 4.

So what does this look like? Well, here you see that I did a ping to; I sent out four pings and got four replies back. And you can see the time it took: 74 milliseconds, 74 milliseconds, 156 milliseconds, and 71 milliseconds, for an average of about 93 milliseconds. All four packets were sent, and all four packets were received, telling me that my web server was up and running successfully at this time. Next, we have traceroute, or trace RT. This is going to display the path between your device, the source, and the destination IP address, showing each router hop along the path. To do this, you just type in “Trace RT” and the IP address. This will display all the routers between you and the computer you’re trying to get to. Now, you can do this by IP address, you can do it by domain name, and like ping, if you use six, it will do it using IPV6 instead. So here’s an example of the Trace route going to It’s worth noting that it automatically resolves the IP address for us. And then it starts tracing out the route from my computer—100, 2, 2, which is my router here—out to that endpoint, which is 5422-1229, 100. Now, notice towards the end from line 15 down that we have a bunch of timeout requests, but my server is up. What does that mean?

Well, for security, a lot of firewalls are told to ignore traceroutes and pings. And so in this case, my web hosting provider for DEON training does not respond to those requests. And so I can only trace it as far as the outermost layer of their network. Once I get to the outermost layer of their network, they stop responding. So I can’t see all the other routers and firewalls going the rest of the way. Next, we have NBT Stat, which is going to display NetBIOS information for IP-based networks. And this is a tool that is only available within Windows. It’s going to display a listing of the NetBIOS device names that are learned by the PC through its communications on the local area network. Now, you can do NBT Stat A and an IP, and that will display the Net BIOS table of that remote PC. If you do NBT Stat C, it’s going to display the PC’s Net BIOS name cache on the local computer. So what does this look like? Well, here’s an example of NBTStat A: 10, 3, 1, one, six.It connects to that remote computer and sees what information it knows. In this case, it knows about a workgroup and a computer called Server Filly, which is its own server.

Next we have Netstat, which stands for network statistics. This is going to display information for IP-based connections on a PC, including its current sessions, its source and destination, and its IPS and port numbers. There are a couple of things you want to know about this. One, A, is going to display all connections and listening ports. Dash N is going to display addresses and port numbers in numerical form. And S is going to just give you statistics on IPV4 and IPV6, TCP versus UDP, and ICMP protocols. So what does all this look like? Well, here’s the dash S.

It’s just a listing of statistics. In this case, you could see the number of packets that were received, sent, and discarded. And it starts breaking that down based on IPV 4, then IPV 6. And if I scroll down, you’ll see TCP, UDP, and ICMP. Now, the one that’s more useful is Netstat ANO. This is the one that I use the most. Notice. It tells me the protocol in the far left column. It tells me my local address or my computer and what it’s listening to. It tells me the foreign address, who it’s connecting to, and the state: is it established, is it closed, or is it listening? If it’s established, that means there’s currently a connection between my machine and somebody else. As you’ll notice, they’re about halfway down the page. And then the PID, because I use the O, tells me who owns that connection.

This is something I use a lot when I’m doing instant response. What is this machine talking about, and who owns it or started that process? And that PID will tell me that if you remember, you used to get A-plus grades. So when you get into security plus or Cysaplus, netstatano is going to become your best friend. Following that, Nslookup, which stands for name server, Lookup will provide us with a fully qualified domain name for an IP address and will resolve it for us.

So if I want to find out what the IP address was for, I can type in Nslookup And this is a non-interactive mode. If I hit Enter, it’s just going to give me that IP address right back. Now it has a second mode, which is called Interactive Mode. And so if you just type in “Nslookup” and hit Enter, it will enter you into this Nslookup shell. This interactive mode gives you much more control over the environment, including the ability to change the server, look it up, and change the type of records you want to respond with.

So if you want to change the server, you change the server and the name. If you want to change the type of record, you’ll set Q equals and the record type. Let me show you what that looks like. So here on the top, you can see I did an NS lookup of It informs me that it will simply default to my DNS server, which it was already using, and returns the IP address. Now, if I do NSlookup and hit Enter, I get into this new prompt with this little carrot. Notice I hit set Q equals MX, which says I want to query MX or mail records only.

Then I asked for mail records, and up came my Mail Exchange servers, which are all hosted by Google because we use Google Suite for our mail programs. See how this works? You can go really, really in depth. Now, the next thing I did was set my query to CNAME, and I asked it for the CNAMEs that are associated with Dion training. and you can see those were shown at the bottom of the screen as well. Nslookup is a very useful tool, especially when you’re doing reconnaissance as you work into analyst and security roles later in your career. Lastly, we have Route, and Route is used to change or display the contents of your PC’s IP routing table. That’s right.

Your Windows PC has a router built into it, and that’s what Route is going to allow you to do. If you type in route print, you can display the contents of the IP routing table. If you do “Route delete” and “IP delete,” it’ll delete that entry. If you want to add a route and tell it where to go, you can say Route add IP, and that tells you to go from one to the other. What does this look like? So, here’s a route I printed from my Windows machine, and take note of the first one: highway 100, route 2. So what’s special about that line? It’s using route zero, which, if you remember correctly, is your default route. Anytime you see 0 in your route table, that is the default route. And so if it doesn’t know anything, it will send traffic out to 100 and 2, which is really important. So in your troubleshooting, if there is no default route, that could be the source of your problem. So always look at the routing table and verify that it’s correct.

  1. UNIX Command Line

Now, in the last lesson, we talked all about Windows tools. But what if you’re using a Mac, a Linux, or a Unix computer? Well, that’s what this lesson is going to be about, and we’re going to talk about the differences between these tools. What is Unix? This is the first question we have to answer.

Well, Unix is an alternate operating system used heavily in the server environment. Unix is also implemented in other operating systems. Unix, BSD, Linux, and even Macintosh OS X, like my machine, are examples. The command syntax that is used between Unix and Windows is often just a little bit different. And so it’s important to see those differences because you may see them on test day. Now, Unix maintains manual pages inside its OS. So if you’re using Unix from the command prompt, you can just type “man” and the command like “man” and “lookup,” and it will give you its manual and teach you what you need to know. Now, when you’re at the command prompt, you’re either going to see a dollar sign or a hashtag. and that’s going to denote that you are at the command prompt.

Notice here in the upper right corner that I am in the bash shell, which is on my OS X, my Macintosh machine. And you’ll see that dollar sign waiting for me to give it a command. Now, when we look at these command-line tools, just like in Windows, they’re used to configure and troubleshoot our networks by issuing these text-based commands. The commands can be used on clients or servers. Again, depending on the operating system, most Unix is fairly compatible with one another. But depending on the variant of Linux, OS X, BSD, or Unix, the commands might vary slightly. The ones I’m going to teach you here are the ones that are covered by the exam. Now, how do you access the command line? If you’re using a Linux or Unix machine, the text-based command line is usually the first place you go. If not, and you have a graphical unit or interface like I do, In the upper right here on my Kali Linux machine, you want to look for that terminal icon, which is in the lower left of that machine on my OS X box, my Macintosh box.

You can find this by opening Spotlight and starting to type the word “terminal,” and it will show up. Or you can go into the applications folder and then under Utilities, and you’ll find the terminal icon, which looks like the lower right image on your screen. The first one we want to talk about is ARP. And we’re not going to spend a lot of time here because it’s exactly the same as Windows. It’s the exact same syntax, and it works exactly the same. So if you learned it last time on Windows, it’s the same thing. ARPA will show you the ARP table, and that will show you your mac addresses and how they link to IP addresses. Then there’s “if config,” yes, “if config,” not “IP confits.” This is not a typo. If config stands for interface configuration, it’s the way that Unix and Linux display IP address information, just like Windows did with Ipconfig. Now if config A works like Ipconfig, giving you all of that information. If you just type “if configuration,” you’ll get a small summarized version.

Now, unlike Windows, there are two other commands with if config that you need to know: if config down and if config up. If you use config down, your network interface card will be turned off. When you finish configuring the card, it will turn back on. And so those are important to realize as well, because if you’re not having any network connectivity, maybe your card has been turned off. So what does the configuration look like when you run it? Notice here at the top that I typed in if config, and under en zero, which I’ve put a red box around, you can see inept six, which is my IPV six address, and inept, which is my IPV four address of 192, 168, and 154. All of the other information is there, such as my broadcast, my subnet mask, et cetera, including my MTU size, which shows that it is 1500. Notice there is much, much more detail here than in the Windows variant. Next we have ping, which is used to check the IP connectivity between two devices and is most often used for troubleshooting. It’s very similar to Windows, but there are a couple of key differences.

If you remember, with Windows, we had a process that would run forever. Well, by default on Linux and Unix, ping will run forever. So if I just ping Jason, it will continue until you type Control. If I do ping C and then the number, it’s like using ping n in Windows. And finally, ping 6 is the IP version, the six version, and it does work the same as Windows for that one. What does ping look like? Well, here it is at ping www dot Jason, and notice it just went off for 10 or 15 or 20 times until I hit control C, and that will bring me back to the command prompt. Next, we have trace routes. Now we’re in Windows. It was Trace RT. Traceroute All is spelled as one word in Unix and Linux. This is going to do the same thing that Traceroute did on Windows. It’s going to display the path between your device, the source, and the destination IP address, showing each hop along the way. Trace route, the IP trace route, and the domain, or traceroute 6 and the domain, will all work similarly to trace RT in Windows. What does that look like?

Well, it’s pretty much the same trace route. It’s not nearly as pretty as the Windows version, but it’s still just as functional. Next, we have Netstat, which is network statistics. This is the exact same as Windows, including the syntax. So netstat, A-N-S, and ANS all work exactly the same. Now, what does Netstat look like? We have a protocol, just like Windows, with send and receive. We have the local address, the foreign address, and any connections that are established. So you can see all those connections that are currently being made with my computer, going from my local computer, which is my workstation, to whatever those web servers are. Next, we have Nslookup and host. Now, Lookup works exactly the same as Windows, but Host is a new one. Host is the simpler version of Nslookup, and it is noninteractive and very, very simple. So you just use Host and the domain name, and I’ll show you what that looks like here on the screen. Host It shows up that is an alias for, which is where my videos are hosted. And then you’ll see that it has an IP address.

Of these four IP addresses, those are the four servers that it knows of, or the four content engines that then link into all the other servers. Next we have Dig, and Dig is yet another way to do name server. Lookup, one of the interesting things you’ll find in Unix and Linux, because it’s an open-source environment, is that there are a lot of different ways to do the same thing. So in windows we had Nslookup.In Linux and Unix, we’ve had Dig and Host and Nslookup, and there are many others that will do the same thing. But Dig is going to resolve this fully qualified domain name to an IP address and give you even more information than Nslookup does. So while Host was giving you very little information, nslookup gave you a medium amount of information, and Dig gave you a lot of information.

Dig does not have an interactive mode, though. So if I wanted to use Dig TMX, that says “Dig the record type of MX mail exchange for” So let’s see what that looks like in the real world. We did Dig Tuxedo training here, and those mail records appeared. And you can see again that they’re being hosted by Google, because Google is our email service provider for our company. Lastly, we have Route, just like we did in Windows. Now, this is used to display the contents of the PC’s IP routing table. If you simply type Route, it will display the contents to the screen in the same way that Windows did with Route print. You can also have Routen, which will display the contents of the routing table, including the default gateway. So here’s an example of Route, and it shows you on the screen. And again, you can see that the default destination of zero zero is going to its default gateway of 5153 23 97. Again, if you don’t have a default gateway, it could be the source of many problems in your network.